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First published in 2013
ePDF ISBN 978 0636 198 197
Pack ISBN 978 0 636 14548 1
Print ISBN 978 0 636 14090 5
Cover design by MML STUDIO
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Artwork by Will Alves, Tanza Crouch and Chris Pheifer
Photos
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Every effort has been made to trace copyright holders. The Publisher apologises
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CONTENTS
INTRODUCTION
vi
1
The Curriculum and Assessment Policy Statement (CAPS) ..........vi
2
How to use this course .....................................................................vi
3
Planning for Natural Sciences .........................................................vii
4
Annual Teaching Plan ......................................................................viii
5
Assessment Framework ...................................................................xii
6
Inclusive education in this course ..................................................xiv
TERM 1
2
TOPIC 1: THE BIOSPHERE.........................................................................3
Unit 1: The concept of the biosphere ........................................ 4
Unit 2: Requirements for sustaining life .................................... 5
Topic 1 revision ......................................................................... 7
TOPIC 2: BIODIVERSITY ............................................................................9
Unit 1: Classification of living organisms................................ 10
Unit 2: Diversity of animals .................................................... 11
Skills focus: Use a classification system ................................... 13
Unit 3: Diversity of plants ...................................................... 13
Topic 2 revision ....................................................................... 14
TOPIC 3: SEXUAL REPRODUCTION ....................................................... 16
Unit 1: Sexual reproduction in angiosperms ........................... 17
Practical: Grow a plant and observe its life cycle..................... 19
Unit 2: Human reproduction .................................................. 20
Skills focus: Draw bar graphs and histograms ......................... 22
Topic 3 revision ....................................................................... 22
TOPIC 4: VARIATION .................................................................................24
Unit 1: Variation exists within a species ................................. 25
Topic 4 revision ...................................................................... 29
TERM 1 PRACTICE TEST MEMORANDUM .............................................30
TERM 2
31
TOPIC 5: PROPERTIES OF MATERIALS .................................................32
Unit 1: Physical properties of materials .................................. 33
Skills focus: Draw line graphs ................................................. 34
Skills focus: Design a fair test.................................................. 35
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Unit 2: Impact on the environment ......................................... 35
Topic 5 revision ....................................................................... 36
TOPIC 6: SEPARATING MIXTURES .........................................................37
Unit 1: Mixtures ..................................................................... 38
Unit 2: Methods of physical separation .................................. 39
Practical task: Design and explain the best ways to separate a
mixture ................................................................................... 42
Unit 3: Sorting and recycling materials ................................... 43
Topic 6 revision ....................................................................... 45
TOPIC 7: ACIDS, BASES AND NEUTRALS..............................................46
Unit 1: Tastes of substances .................................................... 47
Unit 2: Properties of acids, bases and neutrals ........................ 47
Unit 3: Acid-base indicators ................................................... 49
Topic 7 revision ....................................................................... 51
TOPIC 8: THE PERIODIC TABLE OF ELEMENTS....................................52
Unit 1: Arrangement of elements in the Periodic Table ........... 53
Unit 2: Properties of metals, semimetals and non-metals ........ 54
Topic 8 revision ....................................................................... 56
TERM 2 PRACTICE TEST MEMORANDUM .............................................57
TERM 3
58
TOPIC 9: SOURCES OF ENERGY ............................................................59
Unit 1: Non-renewable sources of energy................................ 59
Unit 2: Renewable energy sources ........................................... 60
Topic 9 revision ....................................................................... 60
TOPIC 10: POTENTIAL AND KINETIC ENERGY .....................................62
Unit 1: Potential energy. .......................................................... 63
Unit 2: Kinetic energy ............................................................. 64
Skills focus: Draw energy flow diagrams. ................................. 64
Unit 3: Potential and kinetic energy in systems ....................... 65
Unit 4: The law of conservation of energy .............................. 67
Topic 10 revision ..................................................................... 69
TOPIC 11: HEAT TRANSFER ....................................................................70
Unit 1: Heating as a transfer of energy ................................... 71
Unit 2: Conduction ................................................................. 72
Skills focus: Identify variables that affect results ..................... 73
Practical task: Investigate heat conduction of various metals.. 74
Unit 3: Convection .................................................................. 76
Unit 4: Radiation .................................................................... 77
Topic 11 revision ..................................................................... 79
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TOPIC 12: INSULATION, ENERGY SAVING AND ENERGY TRANSFER
TO THE SURROUNDINGS.......................................................80
Unit 1: Using insulating materials ........................................... 81
Project: Design an energy-efficient home................................. 85
Unit 2: Useful and ‘wasted’ energy .......................................... 87
Topic 12 revision ..................................................................... 89
TOPIC 13: THE NATIONAL ELECTRICITY SUPPLY SYSTEM .................90
Unit 1: Energy transfers in the national grid ........................... 91
Unit 2: Conserving electricity in the home .............................. 92
Skills focus: Conducting a survey ............................................ 93
Topic 13 revision ..................................................................... 94
TERM 3 PRACTICE TEST MEMORANDUM .............................................95
TERM 4
96
TOPIC 14: RELATIONSHIP OF THE SUN TO EARTH ..............................97
Unit 1: Solar energy and Earth’s seasons ................................ 98
Unit 2: Solar energy and life on Earth..................................... 99
Unit 3: Stored solar energy ....................................................100
Topic 14 revision ....................................................................102
TOPIC 15: RELATIONSHIP OF THE MOON TO EARTH ........................ 103
Unit 1: Relative positions of the Moon and Earth .................104
Unit 2: Gravity .......................................................................104
Unit 3: Tides ..........................................................................105
Skills focus: Conduct research................................................106
Unit 4: Tides and ecosystems on the shore .............................106
Practical task: Use diagrams to write about and explain the
effects of the Moon’s gravity on Earth, showing the tides ......107
Topic 15 revision ....................................................................108
TOPIC 16: HISTORICAL DEVELOPMENT OF ASTRONOMY ................ 109
Unit 1: Early indigenous knowledge ......................................110
Unit 2: Modern developments ...............................................112
Topic 16 revision ....................................................................114
MEMORANDA FOR PRACTICE EXAMS
116
Practice exam: Terms 1 and 2 .................................................116
Practice exam: Terms 3 and 4 .................................................117
TEST AND EXAM SECTION
120
Term 1 Test and memorandum ..............................................120
Term 2 Test and memorandum ..............................................123
Term 3 Test and memorandum ..............................................126
Mid-year examination and memorandum ..............................129
End-of-year examination and memorandum .........................134
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INTRODUCTION
THE CURRICULUM AND ASSESSMENT POLICY
STATEMENT
The Curriculum and Assessment Policy Statement (CAPS) is a revision of the National
Curriculum Statement (NCS). In developing the CAPS, a key aim has been to have
just one document providing guidelines for planning, content and assessment for each
subject. The CAPS also continues to support the key principles that underline the
NCS, including: social transformation; high knowledge and high skills; integration
and applied competence; progression; articulation and portablility; human rights,
inclusivity, environmental and social justice; valuing of indigenous knowledge systems
(IKS) and credibility, quality and efficiency.
This Natural Sciences course has been especially developed to comply with the
Curriculum and Assessment Policy Statement (CAPS) for Natural Sciences and
Technology:
•
Work is divided into terms and follows the CAPS sequence.
•
Each term works through topics, covering the required content and skills.
•
Clear guidelines are given on how to carry out the required content.
•
Daily lesson guidelines follow CAPS-specified methodology and time to be spent
on each section of content.
HOW TO USE THIS COURSE
All content as stipulated in the CAPS programme has been covered within this course
and this Teacher’s Guide provides comprehensive advice on how to cover each section
of content with your class. This Teacher’s Guide will also help you with:
•
Planning: The term and topic overviews help you with planning and preparation.
•
Teaching: Follow the weekly lesson guidelines to take you through each part of the
topic being covered.
•
Resources: The resources section refers you to the required Learner’s Book
activities and any other resources like maps, graphs and data you may need to
complete the lesson.
•
Assessment: Formal assessment activities, with assessment tools and teaching
guidelines are provided for each required activity for full CAPS programme of
assessment coverage.
•
Teacher support: Teaching guidelines in the Teacher’s Guide tell you how to use the
Learner’s Book with your learners. Answers and guidance on how to assess learners
has been provided for each activity.
The accompanying Learner’s Book provides additional support and reassurance that
you will be covering everything in the CAPS:
•
Planning: Work for the year is planned across terms and weeks, matching the
required CAPS sequence.
•
Content and skills: Themes are carefully planned to cover the key geographical and
history concepts.
•
Support for learners: Each unit within a topic has helpful key words and summary
activities.
•
Assessment: Formal assessment pages cover the required formal assessment for the
year.
vi
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PLANNING FOR NATURAL SCIENCES
What is Natural Science?
Science is a systematic way of looking for explanations and connecting the ideas that
we have. It involves different methods of inquiry, but always a systematic approach.
Scientists formulate hypotheses, and design and carry out experiments to these
hypotheses. This is an ongoing process, which happens in all cultures and in all times,
and which continues to develop a changing view of the world.
Knowledge Strands
There are four equally important Knowledge Strands in the Natural Sciences
curriculum, each of which is developed with careful progression across each grade in the
Senior Phase.
The Knowledge Strands are:
•
Life and Living (see Term 1);
•
Matter and Materials (see Term 2);
•
Energy and Change (see Term 3);
•
Planet Earth and Beyond (see Term 4).
Links should be made both within and between each Knowledge Strand across the
Senior Phase.
Specific Aims and Skills
Specific Aims
There are three Specific Aims in Natural Sciences, which relate to the purposes and core
skills of learning science, as well as encouraging learners to ask questions that can lead
to further research and investigation:
1. Specific Aim 1: ‘Doing Science’ relates to doing science of practical work and
investigations and to design and make practical solutions to everyday problems.
2. Specific Aim 2: ‘Knowing the subject content and making connections’ relates to the
knowing of the subject content (theory).
3. Specific Aim 3: ‘Understanding the uses of Science’ relates to the understanding of
the applications of science and technology in everyday life, as well as the history of
science and technology discoveries and the relationship between indigenous
knowledge and science and technology.
Across each of these Specific Aims, learners must develop science process skills,
specifically:
•
accessing and recalling information
•
observing
•
comparing
•
measuring
•
sorting and classifying
•
identifying problems and issues
•
raising questions
•
predicting
•
hypothesizing
•
planning investigations
•
doing investigations
•
recording information
•
interpreting information
•
communicating.
Introduction
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This course builds in opportunities to develop these skills throughout the year. Look for the Skills Focus
pages throughout the Learner’s Book.
For more information about the Specific Aims and Skills in the Natural Sciences curriculum, refer to the
CAPS, pages 10–12.
Notional time
The instructional time in the Senior Phase is as follows:
Subject
Hours
Home Language
5
First Additional Language
4
Mathematics
4,5
Natural Sciences
3
Social Sciences
3
Technology
2
Economic Management Sciences
2
Life Orientation
2
Creative Arts
2
Total
27,5
This Teacher’s Guide indicates how to plan to deliver the Natural Sciences curriculum within this allocated
instructional time.
ANNUAL TEACHING PLAN
The following Annual Teaching Plan provides a suggested plan for covering content in this course. This
can be used as a starting point for your own individual planning. There are also Skills Focus pages planned
throughout the course to support the development of all critical science skills throughout the year, as
described in the CAPS document.
Annual Teaching Plan Term 1
viii
Week
Topic: Units
Description
Time
allocation
1
Topic 1: Unit 1
The biosphere: The concept of the biosphere
1,5 hours
Topic 1: Unit 2
The biosphere: Requirements for sustaining life
1,5 hours
2–3
Topic 2: Unit 1
Biodiversity: Classification of living organisms
4,5 hours
3–4
Topic 2: Unit 2
Biodiversity: Diversity of animals
3 hours
4–5
Topic 2: Unit 3
Biodiversity: Diversity of plants
3 hours
5–6
Topic 3: Unit 1
Sexual reproduction: Sexual reproduction in angiosperms
3,5 hours
6
Practical task
Grow a plant and observe its life cycle
1 hour
7–8
Topic 3: Unit 2
Sexual reproduction: Human reproduction
6 hours
9
Topic 4: Unit 1
Variation: Variation exists within a species
3 hours
10
Revision
2 hours
10
Term 1 Practice test
1 hour
Introduction
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Annual Teaching Plan Term 2
Time
allocation
Week
Topic: Units
Description
1
Topic 5: Unit 1
3 hours
2
Topic 5: Unit 1
Properties of materials: Physical properties of
materials
Properties of materials: Impact on the environment
3–4
Topic 6: Unit 1
Separating mixtures
2 hours
4–5
Topic 6: Unit 2
Practical task
Separating mixtures: Methods of physical separation
Design and explain the best ways to separate a
mixture
2 hours
1 hour
5–6
Topic 6: Unit 3
Topic 7: Unit 1
Separating mixtures: Sorting and recycling materials
Acids, bases and neutrals: Tastes of substances
2 hours
2 hours
Topic 7: Unit 2
Acids, bases and neutrals: Properties of acids, bases
and neutrals
2 hours
6–7
Topic 7: Unit 3
Acids, bases and neutrals: Acid-base indicators
2 hours
7–8
Topic 8: Unit 1
3 hours
8–9
Topic 8: Unit 2
The Periodic Table of Elements: Arrangement of
elements in the Periodic Table
The Periodic Table of Elements: Properties of metals,
semimetals and non-metals
9–10
Revision
3 hours
10
Term 2 Practice test
1 hour
10
Practice exam: Terms
1 and 2, Mid-year
examination
2 hours
3 hours
3 hours
Introduction
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Annual Teaching Plan Term 3
Topic: Units
Description
1
Topic 9: Unit 1
Sources of energy: Non-renewable sources of
energy
1,5 hours
Topic 9: Unit 2
Sources of energy: Renewable sources of energy
1,5 hours
Topic 10: Unit 1
Potential and kinetic energy: Potential energy
1,5 hours
Topic 10: Unit 2
Potential and kinetic energy: Kinetic energy
1,5 hours
Topic 10: Unit 3
Potential and kinetic energy: Potential and kinetic
energy in systems
1,5 hours
Topic 10: Unit 4
Potential and kinetic energy: The law of
conservation of energy
1,5 hours
Topic 11: Unit 1
Heat transfer: Heat as a transfer of energy
1,5 hours
Topic 11: Unit 2
Heat transfer: Conduction
1,5 hours
Practical task
Investigate heat conduction of various metals
1 hour
Topic 11: Unit 3
Heat transfer: Convection
1 hour
2
3
4
5
x
Time
allocation
Week
Topic 11: Unit 4
Heat transfer: Radiation
1 hour
6
Topic 12: Unit 1
Insulation, energy saving and energy transfer to
the surroundings: Using insulating materials
3 hours
7
Project
Design an energy-efficient home
3 hours
8
Topic 12: Unit 2
Insulation, energy saving and energy transfer to
the surroundings: Useful and ‘wasted’ energy
3 hours
9
Topic 13: Unit 1
The national electricity supply system: Energy
transfers in the national grid
1,5 hours
Topic 13: Unit 2
The national electricity supply system:
Conserving electricity in the home
1,5 hours
10
Revision
2 hours
10
Term 3 Practice test
1 hour
Introduction
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Annual Teaching Plan Term 4
Time
allocation
Week
Topic: Units
Description
1–2
Topic 14: Unit 1
Relationship of the Sun to the Earth: Solar
energy and Earth’s seasons
2–3
Topic 14: Unit 2
Relationship of the Sun to th Earth: Solar energy 4 hours
and life on Earth
3–4
Topic 14: Unit 3
Relationship of the Sun to the Earth: Stored
solar energy
4 hours
5
Topic 15: Unit 1
Relationship of the Moon to the Earth: Relative
positions of the Moon and the Earth
1,5 hours
Topic 15: Unit 2
Relationship of the Moon to the Earth: Gravity
1,5 hours
Topic 15: Unit 3
Relationship of the Moon to the Earth: Tides
1 hour
Topic 15: Unit 4
Relationship of the Moon to the Earth: Tides and 1 hour
ecosystems on the shore
Practical task
Use diagrams to write about and explain the
effects of the Moon’s gravity on the Earth,
showing the tides.
1 hour
Topic 16: Unit 1
Historical development of astronomy: Early
indigenous knowledge
1 hour
Topic 16: Unit 2
Historical development of astronomy: Modern
developments
1 hour
6
7
4 hours
8–9
Revision
5 hours
10
Practice exam: Terms 3 and 4,
End-of-year examination
4 hours
Introduction
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ASSESSMENT FRAMEWORK
Informal Assessment
Informal assessment is a daily monitoring of learners’ progress. This is done
through observations, discussions, practical demonstrations, learner-teacher
conferences, informal classroom interactions, and so on. Informal assessment
may be as simple as stopping during the lesson to observe learners or to discuss
with learners how learning is progressing. Informal assessment should be used to
provide feedback to the learners and to inform planning for teaching, but need not
be recorded.
Formal Assessments
Programme of Assessment
The Programme of Assessment is designed to spread formal assessment task in
all subjects in a school throughout a term. It consists of formal, recorded schoolbased assessments (40%) and end-of-year internal school-based examinations
(60%). For Natural Sciences, this is organised across the year as described below.
School-based
assessments
Term 1
Term 2
Term 3
Term 4
Test 1
Test 2
Test 3
Practical task/
Investigation 4
Practical task/
Investigation 1
Practical task/
Investigation 2
Practical task/
Investigation 3
Exams
Number
of formal
assessments
Exam
2
3
2
Percentage
for the year
40%
Project
Exam
60%
3
100%
For more information about Formal Assessment in the Natural Sciences
curriculum, refer to the CAPS, pages 85–93.
Recording and reporting
Within the Senior Phase teachers should use the 7-point rating scale (see below)
to record learners’ achievement. Marks should be recorded against the task by
using a record sheet, and percentages should be noted against the subject on the
learners’ report cards.
xii
Rating code
Description of competence
Percentage
7
Outstanding achievement
80–100
6
Meritorious achievement
70–79
5
Substantial achievement
60–69
4
Adequate achievement
50–59
3
Moderate achievement
40–49
2
Elementary achievement
30–39
1
Not achieved
0–29
Introduction
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How this course helps you with assessment
The Natural Sciences Programme of Assessment is built in throughout each term
of the course, exactly where you need them.
At the end of every topic is also a revision section, which is laid out in the
form of a test. You can use this to consolidate learning and also as preparation for
the class tests and that are required in the Programme of Assessment each term,
and as a basis for compiling the mid-year and end-of-year examinations.
Grade 7
Term 1
Term 2
Term 3
Term 4
Learner’s Book page number
Practical task 1: Grow a plant and observe its life cycle
38
Term Test
63
Practical task 2: Design and explain the best ways to separate
a mixture
89
Term test
123
Practical task 3: Investigate heat conduction of various metals
155
Project: Design an energy-efficient home
174
Term test
191
Practical task 4: Use diagrams to write about and explain the
effects of the Moon’s gravity on Earth, showing the tides
224
The project can be done at any time in the year, but the mark for this should be
recorded in Term 4. See CAPS pages 88–89 for further information on managing
this.
Full exam papers for Term 2 and Term 4 are provided at the back of this
Teacher’s Guide and can be copied and distributed to the class. Additional practice
tests have been provided for Terms 1–3 as further revision for the end-of-year
exam. Memoranda for all assessments are included in this Teacher’s Guide.
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INCLUSIVE EDUCATION IN THIS COURSE
Our schools are all different, however, what we have in common is that there are
generally many learners in mainstream classes who experience barriers to learning.
These barriers differ depending on a range of circumstances. It is important to
understand and acknowledge the main barriers to learning in your class. We
suggest you draw up a profile of your class to help you identify and understand
the main barriers to learning in your particular class. The table below will help
you to get a general idea of the barriers preventing learning, of course some of
the difficulties may be small, whereas others may be more extreme. For example,
you may have a learner with a minor hearing loss in one ear, requiring minimal
support or you could have a learner with a severe loss in both ears requiring far
more support. Additional advice can be gained from your local education office on
management of barriers to learning.
Type of barrier
Examples
Physical
Hearing loss; visually impaired; chronically sick; unable to walk and
needs a wheelchair
Cognitive
Mentally challenged; specific learning difficulties: this could be due
to a syndrome such as foetal alcohol syndrome (FAS)
Specific academic
experiences/
difficulties
Gaps in learning, for example, a learner may have missed school
during the early years and subsequently has limited reading and
writing skills
Psychological/
emotional
Too many experiences of failure – no motivation; post-traumatic
stress; depression
Involving the
family or society
Family moves continuously; natural disaster for example fire or
floods; physical or sexual abuse at home; excessive violence at
home/in the community; hunger, neglect and general deprivation
Specific language
issues
The language of learning and teaching (LOLT) is different from the
learner’s home language and the learner is not fluent in the LOLT
For most teachers, the most difficult aspect of inclusive education is classes having
a very diverse range of learners with different abilities, as well as different types
of barriers to learning. Below are some practical suggestions for accommodating
diversity in your classroom.
•
Create a safe working environment. Praise whenever possible and make
positive comments; notice positive behaviour (and don’t just focus on the
negative behaviour).
•
Create a positive atmosphere of mutual respect and trust in your classroom
with ground rules, for example:
— Learners laugh together, never at each other.
— Do not allow teasing or bullying.
— Most important, there should be only one speaker at a time who is
listened to closely.
•
Develop ‘team’ relationships between the learner, educator, parent – anyone
working towards the success of the learner.
•
We all receive information, process and express information differently,
depending on our learning styles. Keep in mind that in your class there will be
learners whose learning style is different from your own.
xiv
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•
•
•
•
Set up different group work systems.
— Same-ability groups: This is useful when learners are working on a task
that develops specific skills. It enables you to adjust the task slightly,
depending on the level of the group. It also enables groups of learners to
work at different paces.
— Mixed-ability groups: These work well for tasks, projects and activities
where you want learners to work together and learn from each other.
Allow learners to help each other.
Train learners in your class to become tutors and introduce peer tutoring.
You may want to train learners from higher grades to become tutors or
develop a volunteer system using willing and able adults from the community.
This course helps you teach learners of diverse abilities in the following ways:
•
A range of activities are provided to cater for different learning styles.
•
There are opportunities for group, pair and individual work.
•
There are many opportunities to develop and practice the same skill. This is
based on the spiral approach to learning where learners are exposed to the
same concepts and skills, but in increasing complexity throughout a grade and
phase.
•
Key words and their definitions are listed on the relevant pages and in the
glossary at the back of the Learner’s Book. These definitions assist learners’ to
understand the key words covered in each unit.
•
Each unit of work has a short activity that is completed at the end of the unit
to assist the learner with consolidating their knowledge.
•
Revision activities are used to consolidate a whole topic once it has been
taught.
•
Case studies assist in getting the learners to relate to real life occurrences, the
consequences thereof and allow learners to come up with relevant solutions.
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TERM 1
Within Term 1, your Grade 7 learners will cover the following sections of content:
Strand
Topics and time
allocation
Unit
LB page
Life and Living
1 The biosphere
Unit 1: The concept of the biosphere
2
(3,5 hours)
Unit 2: Requirements for sustaining life
4
2 Biodiversity
Unit 1: Classification of living organisms
10
(5,25 hours)
Unit 2: Diversity of animals
14
Unit 3: Diversity of plants
22
3 Sexual reproduction
Unit 1: Sexual reproduction in angiosperms
30
(12,25 hours)
Unit 2: Human reproduction
40
4 Variation
Unit 1: Variation exists within a species
56
(3,5 hours)
TERM 1 ASSESSMENT
The following Formal Assessment Tasks will need to be completed in Term 1. You may use the examples
in this book for your learners or you may want to develop your own.
2
Formal assessment Task
Mark allocation
Learner’s book page
Teacher’s guide page
Practical task: Grow a plant and
observe its life cycle
30
38
19
Term 1 Practice test
30
63
30
Term 1
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TOPIC 1: THE BIOSPHERE
Topic overview
Earth is made up of four systems: the biosphere, lithosphere (land), the atmosphere (air) and the
hydrosphere (water). These systems interact with one another. The biosphere is the part of Earth where
life occurs. It consists of all the living things and their relationships with the atmosphere, lithosphere and
hydrosphere. There is an enormous variety of life, including animals, plants and micro-organisms.
Living organisms carry out seven life processes: nutrition, growth, reproduction, respiration,
excretion and sensitivity to the environment. To sustain life, living things require energy, gases, water, soil
and a favourable temperature. This is provided by the environment in which an organism lives. Living
things are adapted to the environment in which they live.
Common errors learners make
The concept of the biosphere and how it interacts with the other three systems can be misunderstood by
learners.
The way in which living things interact and with non-living things in an environment: Make sure the learners
understand concepts by demonstrating how things interact with one another and thus reinforce the
overarching concept of Earth as a system. Explain what a system is using a bicycle. Explain that a bicycle
is made up of different parts, which all do slightly different things. However, all the parts together help
transport a person over a distance. In the same way as the bicycle, the parts that make up the biosphere
interact. The parts of the biosphere include living organisms and non-living factors such as water, space,
soil and air. These non-living parts are found in the atmosphere, hydrosphere and lithosphere.
Adaptations: learners sometimes believe that, if a plant or animal needs an adaptation, then it can
simply ‘develop one’. This is incorrect. It is important to explain how changes or variations that happen
in populations happen by chance and can sometimes be useful in helping an organism survive. These
changes or variations are eventually passed on to younger generations until the whole population has the
change. It is therefore important to discuss this happening in a whole population and not just individuals.
Also it does not occur overnight – it occurs over a longer time period. Variations are discussed in Topic 4
but you could touch on this in this topic to ensure that the learners understand it. You can use zebra as an
example of a species in which variation occurs. Some individuals are born very dark and some very light.
If this change helps them hide from predators, they will survive, so this characteristic will be passed on to
their young, and so on. Eventually, the whole population will have the characteristic that helps them hide
from predators.
Resources for this topic
•
•
•
•
•
•
•
•
Pictures and photographs of Earth and its biosphere
Posters of the biosphere
Video clips
Seeds
Soil
Containers for growing seeds
Rulers or measuring tapes
Textbooks and other reference materials
Suggestions for additional resources
Use containers such as yoghurt or margarine pots, or egg boxes in which to grow seeds.
Topic 1: The biosphere
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Starting off
Teaching guidelines
This activity aims to introduce learners to the idea of the biosphere and the interactions between living
and non-living things. Use posters and pictures including Figure 1 in the Learner’s Book. The activity will
help you find out what the learners already know.
Activity 1: Identify areas where life is found
LB page 1
Answers
1.
2.
3.
4.
Living things are found in the air, on land and in water.
In the sea, there may be any of the following: seaweeds, starfish, whelks, limpets, fish, sharks, whales
or seals. In the air, there may be a variety of different kinds of insects, birds, mammals and microscopic organisms such as bacteria. You can find a variety of insects, birds, mice, moles and lizards
living on land.
Kudu eat leaves, twigs and seeds of trees. It is a browser. Zebras eat grass. They are grazers.
Springbok eat both grass, small plants and leaves and seeds of trees.
‘Adapted’ means that a plant or animal is structurally and/or behaviourally suited to survive in its
environment.
Unit 1: The concept of the biosphere
Teaching guidelines
Introduce this section by asking questions such as ‘What makes up the Earth?’ and ‘What is a system?’
Show learners pictures and photographs of the Earth and the different components. Use the concept of a
bicycle to explain what a system is, and how the different parts work together and are interdependent. If
you can, show learners some video clips of the biosphere:
http://www.travelvideo.tv/videos/quebec/biospherevideo.html
Activity 2: Describe components of Earth’s biosphere
LB page 2
Answers
1.
2.
3.
4.
4
Hydrosphere, lithosphere, atmosphere
The hydrosphere is all of the water found on Earth in rivers, lakes and oceans. It also includes the
moisture in the air. The lithosphere is the thin layer of rock and soil that covers Earth.
The atmosphere is the thin layer of gases that surrounds Earth. It consists mainly of the gases
nitrogen, oxygen and carbon dioxide.
Biosphere
Ecosystems, which include all of the living things that live in a specific area and their interactions
with each other and their non-living environment.
Term 1
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Activity 3: Identify living organisms in each sphere
LB page 3
Answers
1.
Lithosphere
Hydrosphere
Atmosphere
Animals
Cows, dogs, zebra, lion
Fish, whales, dolphins,
turtles, tadpoles
Birds, insects, bats
Plants
Flowering plants (grasses,
trees), ferns, mosses
Seaweeds, reeds, algae,
water lilies
Seeds of plants
2.
Nutrition, growth, reproduction, respiration, excretion, sensitivity, movement
Support for this unit
Because there is a lot of new terminology in this unit, ask the learners to make a list of all of the words
in bold and to write definitions for each of them. Ask those learners who are still struggling with
terminology to write sentences using these words.
Extension for this unit
The learners can design simple posters to show what they understand by the term ‘biosphere’. They can
explain their posters to the class.
Unit 2: Requirements for sustaining life
Teaching guidelines
This unit is about the needs of living things and how these needs are provided by the non-living part of
the environment. Explain to the learners what these needs are and then tell them that they will investigate
whether seedlings need water and light to grow. Divide the class into groups of between two and four
learners. About half of the groups should investigate the effect of light, and the other half the effect of
water on the growth of radish seeds. Ask them to bring some of the materials, such as containers, from
home. Have all of the materials set out in the front of the class, so that the learners can collect what they
need. Set aside an area where they can leave their containers so that they will not be disturbed. Get the
learners to tidy up after they have set up their investigations. This means that the class will need to tidy
their workspace about 10 to 15 minutes before the end of the lesson. Nominate some monitors to help
make sure that the area is completely clean.
Revise the steps of an investigation with the learners. These include formulating a hypothesis, making
a prediction, identifying variables and ensuring that the test is fair. Refer the learners to pages 153–154 in
the Learner’s Book so that they can check anything that they are not sure about. Encourage them to find
answers to their queries before asking you.
Explain the concept of adaptation by using examples such as pictures of plants and animals, or by
finding living specimens in the school grounds to show to the learners. Ask them questions like ‘What do
you think an adaptation is?’ Show them some pictures and take care that your explanations do not lead to
misconceptions. They will learn more about adaptations in Grade 8, so it is important to get this concept
correct.
The following site contains some PowerPoint slides and is a useful site to show learners:
http://www.biologyjunction.com/unit9_ecology.htm#POWERPOINTS
Topic 1: The biosphere
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Activity 4: Investigate requirements of seedlings for growth
LB page 5
Answers
1.
2.
3.
Plants need sunlight and water so that they can grow.
The amount of water OR sunlight, temperature, type of soil, wind and amount of space.
The independent variables are the amount of water OR sunlight, and the dependent variable is the
height of the seedlings.
The seedlings kept in the dark may grow the tallest, but they will not be healthy. The seedlings
receiving light and water will be the strongest plants..
All of the variables that can affect the outcome of the experiment, besides light and water, will be
kept the same. They will be controlled.
4.
5.
11. Here is an example of the kind of answer to expect.
Average height of seedlings (mm)
Day
Container A
Container B
Container C
Container D
1
0
0
0
0
2
(1,5 + 2 + 1,1 + 1,6)
4
= 1,55
0
(0,5 + 0,6 + 0,4 + 0,7)
4
= 0,55
0
4
(2 + 2,1 + 2,5 + 2,7 + 2.3)
5
= 2,32
0
(1 + 0,9 + 0,6 + 1)
4
= 0,875
0
6
(5 + 5 + 7 + 8)
4
= 6,25
0
(1,8 + 2 + 0,9 + 1,7)
4
= 1,6
0
8
(9 + 9,2 + 10 + 11)
4
= 9,8
0
(2,3 + 2,5 + 1,8 + 2,1)
4
= 2,175
0
10
(12 + 12.5 + 12 + 14)
4
= 9,8
0
(2,9 + 3,1 + 2,4 + 2,7)
4
= 2,775
0
12. Yes, seedlings need water and light to grow into healthy plants. This supports the hypothesis. The
seeds that received no water did not germinate. The seeds that received water but no light did
germinate, but they were not strong, green plants.
13. They could plant more seeds to improve the reliability of the results. They could also use string or
cotton to measure the seedlings and then measure the string or cotton with a ruler to get more
accurate results.
6
Term 1
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Activity 5: Describe adaptations
LB page 7
Answers
1.
2.
An adaptation is a characteristic that helps a living thing survive in its environment. Adaptations can
be structural, behavioural or physical. Adaptations happen by chance but if they help an organism to
survive and reproduce, then the characteristic is passed on to the organism’s young.
a) The camelthorn has long thorns that discourage animals from eating it; OR it has small leaves
that help it not to lose too much water.
b) A gemsbok can survive for weeks without drinking water. It gets water from the plants that it
eats. It feeds on plants early in the morning when their water content is higher than during the
rest of the day. A network of blood vessels in its nose helps to cool its blood before it flows to the
brain. This prevents the gemsbok from overheating in hot conditions. The camel thorn tree has
long roots to reach underground water and small leaves to reduce the loss of water. It also has
long thorns to protect it from herbivores.
Support for this unit
Learners often struggle with the concept of adaptations. Ask them to write their own explanation of an
adaptation and check what they have written, looking out for any misconceptions. Give examples of more
adaptations. For example, locusts are green or brown so that they are not easy to see (camouflaged) and
this helps them survive because their predators cannot easily spot them.
Extension for this unit
Learners can find examples of animals and plants in the school grounds and explain to the class how they
are adapted to survive in their environment. Check their work before they present their answers to make
sure that there are no errors in their explanations.
TOPIC 1 REVISION
LB page 8
Science language activity
Answers
1.
2.
Hydrosphere: water
Atmosphere: air
Lithosphere: land
Lithosphere: thin layer of soil and rocks that covers the surface of Earth; hydrosphere: all of the
water found on Earth; atmosphere: thin layer of gases that surrounds Earth; biosphere: all of the
areas on Earth where life exists; decomposers: organisms that break down dead plant and animal
matter, such as bacteria and fungi; micro-organisms: tiny organisms that live in the biosphere; species:
a group of organisms that look alike and can reproduce together; nutrition: process of getting food;
respiration: process that produces energy from food; excretion: removal of waste substances from the
body; photosynthesis: the process in which plants use light energy from the sun to make their own
food; adaptation: a characteristic that helps a living thing
survive in its environment
Topic 1: The biosphere
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Test yourself
Answers
1.
2.
3.
4.
a) The biosphere is all the areas on Earth where life is found.
b) geosphere, atmosphere and hydrosphere
c) They are needed in order for living organisms to survive.
d) It contains all the biodiversity and is the global ‘sum’ of all ecosystems on Earth.
Fish have fins for swimming in water and they have gills for getting oxygen from the water.
They have a streamlined body shape so that they can move fast.
a) It has a long thin beak to reach nectar deep inside flowers.
b) It has brightly coloured and shiny feathers.
c) It has wings covered with feathers, which help to increase the surface area for flying. It has a
streamlined shape.
a) Temperature
b) The height of the seedlings. It was measured with a ruler or tape measure.
c) The test must be fair so that we know which variable caused the changes to the dependent
variable. We only know this if one factor is changed at a time.
d) Plants will grow better in warmer temperatures.
e) Results
Container
A
B
C
D
Height of seedlings (cm)
0
0
2,5
4
(2)
(3)
(1)
(2)
(6)
(2)
(1)
(2)
(1)
(2)
(3)
(2)
(5)
f)
The bar graph should have the following components:
• a heading: The height of seedlings grown at different temperatures
• x-axis units: A, B, C, D)
• x-axis label: Temperature (°C)
• y-axis units: 0, 2, 3, 4
• y-axis label: Height of seedlings (cm).
Learners should draw bars that correspond to the values in table above.
(8)
Total: 40
8
Term 1
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TOPIC 2: BIODIVERSITY
Topic overview
There are many different types of living organisms that exist on Earth. These organisms are classified
or grouped according to their similarities and differences. This allows us to study and understand them
more easily. Living organisms are first grouped into five kingdoms and then into more specific groups
within each kingdom. All the plants and animals that belong to a particular group will have similar
characteristics or features.
Common errors learners make
Learners may make mistakes when they classify of organisms if they are not completely familiar with
the characteristics of each particular group. For example, they may group spiders and insects in the
same group. Spiders, however, belong to the class arachnids and although they are arthropods, they are
not insects. Learners must ensure that they are familiar with the general characteristics of each of the
particular groups in order to be able to classify living organisms correctly.
Resources for this topic
•
•
•
•
•
•
•
1 land snail per group of learners
1 dish or bowl per group of learners
1 beaker of water per group of learners
1 hand lens per group of learners
A variety of seeds per learner, for example lentils, kidney beans, sugar beans, maize or peas
Ten different species of plants per group of learners
Pictures and photographs of vertebrates and invertebrates (Some are provided in the Learner’s Book.)
Suggestions for additional resources
•
•
Photographs off the Internet
Photographs from library books
Starting off
Activity 1: Group living organisms based on shared characteristics
LB page 9
Answers
2.
Plants
Animals
Trees
Frogs
Grass
Dragonflies
Ferns
Dove
Bushbuck
Lizard
3.
4.
5.
6.
The learners can give any two characteristics that all the animals share. For example, they all have
heads and legs, they all have eyes and they can all move around.
The learners can give any two characteristics that the plants share. For example, they have green
leaves, they cannot move around and they have roots and stems.
a) Have hair: bushbuck; do not have hair: lizard, frog, dragonfly, dove
b) Have feathers: dove; do not have feathers: frog, dragonfly, bushbuck, lizard
c) Have naked skin: frog; do not have naked skin: dragonfly, dove, bushbuck, lizard
High biodiversity; there are lots of different types of organisms living in the ecosystem.
Topic 2: Biodiversity
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Unit 1: Classification of living organisms
Teaching guidelines
In order to help the learners understand classification, start by asking them to group familiar objects. This
activity of grouping can be practised repeatedly until the learners understand the concept of grouping
things using different criteria. Once this is understood, the learners can learn how living organisms are
grouped by starting with the broader categories or kingdoms. They can then learn how the organisms
within the plant and the animal kingdoms are grouped into more specific groups.
Activity 2: Group a selection of everyday objects
LB page 10
Answers
1.
Objects that are used in sports
Objects that are used for eating
and serving food
Objects that are worn
Soccer ball
Spoon
Sunglasses
Rugby ball
Plate
Lipstick
Sunglasses
Sports cap
Sports cap
2.
3.
4.
The following groups are correct:
Fabric objects: sports cap
Plastic objects: soccer ball, rugby ball, sunglasses, lipstick
Porcelain objects: ceramic plate
Metal objects: spoon
The following groups are correct:
Pink and gold: ball, lipstick
White: plate, rugby ball
Brown: sunglasses, cap
Silver: spoon
Grouping objects according to what they are used for is the easiest.
Activity 3: Develop a mnemonic to remember the classification levels
LB page 12
Answers
The learners should develop their own mnemonics to help them remember the seven levels of
classification. An example of a mnemonic is provided in the Learner’s Book to assist them.
10
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Activity 4: Tabulate the basic differences between plants and animals
LB page 13
Answers
1.
Plants
Animals
Remain rooted in one place
Are able to move around
Absorb water and mineral salts from the soil through
their roots
Get water and mineral salts by drinking water and
eating food
Are green in colour and make their own food by the
process of photosynthesis
Are not green in colour and cannot make their own
food; get food by eating other plants and animals
Reproduce by producing spores or seeds
Reproduce by giving birth to live young or laying
eggs, or by simply dividing into two
Unit 2: Diversity of animals
Teaching guidelines
Explain to the learners that the focus of this unit is the many different types of animals that live on Earth.
Explain that the animal kingdom is divided into vertebrates and invertebrates. Vertebrates are animals
that have a backbone and these include fish, amphibians, reptiles, birds and mammals. Invertebrates are
animals that do not have a backbone and these include arthropods and molluscs.
Activity 5: List the characteristics that distinguish the classes of vertebrates
LB page 17
Answers
1.
Distinguishing
characteristics of the
classes of vertebrates
Fish
Amphibians
Reptiles
Birds
Mammals
Divisions of the body
Head, trunk
and tail
Head, trunk
and tail
Head, trunk
and tail
Head, trunk
and tail
Head, trunk
and tail
Type of body covering
Scales
None/naked
skin
Scales
Feathers and
scales on
legs
Hair or fur
Number and types of limbs
Fins
Four limbs
Four limbs
Two legs,
two wings
Four limbs
Cold-blooded or warmblooded
Cold-blooded
Cold-blooded
Cold-blooded
Warmblooded
Warmblooded
Type of reproduction (lays
eggs or gives birth to live
young)
Lays eggs
Lays eggs
Lays eggs
Lays eggs
Gives birth
to live young
Organs used for breathing
Gills
Gills and
lungs
Lungs
Lungs
Lungs
Topic 2: Biodiversity
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Activity 6: Observe and describe the land snail
LB page 19
Answers
1.
2.
3.
Make sure that the learners’ drawings are neat and include the following labels: head, tentacles,
eyes, mouth, muscular foot, shell.
The snail has a head at one end and a tail at the other. The head has a mouth and two sets of
tentacles. The longer set of tentacles has the eyes on the end of them. The body is strong and
muscular, and it forms a strong foot that the snails move around on. The top of the body is covered
by a hard, spiral-shaped shell.
The foot feels tough and strong. It is slimy because it is covered by mucous that is secreted by the
snail. The snail’s skin is quite rough. The shell is hard and spiral in shape. It feels ridged.
Activity 7: List the distinguishing characteristics of the four groups of invertebrates
LB page 19
Answers
1.
Organism
(a)
(b)
(c)
(d)
Group of invertebrate
Insect
Arachnid
Crustacean
Mollusc
Visible characteristics
used to identify the
invertebrate
• Head, thorax
and abdomen
• Two body segments:
the cephalothorax
and the abdomen
• Five pairs of legs
• Soft body
• Jointed legs
• Shell
• Four pairs of legs
• Cephalothorax
and abdomen
• Tentacles
• No antennae or
wings
• Two pairs of
antennae
• One pair of
antennae
• Three pairs of
legs
• Eyes are on
stalks
12
Term 1
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Skills focus: Use a classification system
Activity 8: Classify living things using a numbered key
LB page 20
Answers
1.
A:
B:
C:
D:
E:
F:
G:
H:
I:
ostrich
cheetah
giant bullfrog
shark
eagle
horse
crocodile
praying mantis
spider
Unit 3: Diversity of plants
Teaching guidelines
Explain to the learners that, in the same way that the animal kingdom is grouped, plants are also grouped
into more specific groups. Some groups of plants are mosses, ferns, angiosperms, or flowering plants, and
the gymnosperms, or cone-bearing plants. Plants that produce seeds are referred to as ‘seed plants’ and
include the angiosperms and the gymnosperms. All the other plant groups do not produce seeds, and are
grouped together as ‘seedless plants’. Mosses and ferns are seedless plants. Although they are all plants,
they have differences, which categorises them in different groups. The angiosperms can be further divided
into monocotyledonous plants and dicotyledonous plants.
Activity 9: Identify and describe the difference between monocotyledonous and
dicotyledonous seeds
LB page 24
Answers
1.
2.
3.
For example: Lentil, bean, barley or maize
Lentil, bean: two cotyledons; maize, barley: one cotyledon
Lentil, bean: dicotyledonous seeds; maize, barley: monocotyledonous seeed
Activity 10: Identify and describe the observable differences between plants
LB page 27
Answers
1.
2.
The learners should sort the plants into two groups, monocotyledons and dicotyledons.
Learner’s should draw simple diagrams to show what the monocotyledonous and the dicotyledonous
plants look like. Their diagrams should be similar to Figures 29 and 31 in the Learner’s Book.
Topic 2: Biodiversity
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3.
4.
The learners should provide reasons as to why their plants are monocotyledonous or dicotyledonous.
Monocotyledonous plants
Dicotyledonous plants
Roots
Adventitious root system
Taproot system
Stems
Stems are underground or
runners.
Stems become hard and woody
Leaves
Leaves are attached to the stem
with a leaf sheath.
Leaves are attached to the stem
with a petiole.
Leaves are long and strap-like.
Leaves are not long and straplike, but have a variety of shapes.
Leaves have parallel veins.
Leaves have net veins.
Flowers
Flower parts are arranged in
threes, or multiples of three.
Flower parts are arranged in fours
or fives or multiples of this.
5.
Angiosperms
Gymnosperms
Produces flowers
Produces cones
Leaves have a variety of shapes.
Leaves are shaped like needles.
Plants can be small herbs to large trees.
Large plants and trees.
Extension for this unit
Ask the learners to do a project in groups to highlight the biodiversity of plants and animals in South
Africa. The learners should choose one specific group that they have studied. For example, any one type
of vertebrate, invertebrate or plant. They should then research at least five different species that belong
to this group. A photograph of each example could then be arranged on a poster along with its scientific
name and common name. Each group should choose a different group of plants or animals to research.
Once completed, all the posters can be displayed in the classroom. When placed together, the posters will
give an indication of the incredible diversity of living organisms that occurs in South Africa.
TOPIC 2 REVISION
LB page 28
Science language activity
Answers
1.
2.
14
Living organisms are grouped or classified to make it easier for biologists to study them. Biologists
group living organisms according to their similar characteristics.
a) Animals that have a backbone
b) Animals that do not have a backbone
c) Soft-bodied organisms that have either internal or external shells
d) An arthropod with an exoskeleton, three body regions, segmentation and many pairs of jointed
legs
e) A flowering plant
f) A plant that produces cones and naked seeds
g) Flowering plant that has two cotyledons in the seed
h) Flowering plant that has one cotyledon in the seed
Term 1
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Test yourself
Answers
1.
2.
3.
a) Bacteria, protists, plants, fungi, animals
b) Animal
c) Ferns: plant; humans: animal; mushrooms: fungi; beetles: animal
The following characteristics should be included in the paragraph:
• Nostrils lead to lungs for breathing.
• They are warm-blooded.
• The body is covered with hair or fur.
• Females produce milk in mammary glands and suckle their young.
• They have teeth with roots.
a) B
b) It has a taproot. Its leaves have net veins and are attached to the stem with a petiole.
There are five petals in the flower.
c) A
d) It has an adventitious root system. Its leaves have parallel venation. Leaves are attached to
the stem with a leaf sheath. There are six petals in the flower.
(5)
(1)
(4)
(5)
(1)
(4)
(1)
(4)
Total: 25
Topic 2: Biodiversity
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TOPIC 3: SEXUAL REPRODUCTION
Topic overview
Most living organisms reproduce sexually. This involves the production of male and female sex cells
and then the fusion of these cells in a process called fertilisation. Both plants and animals have special
structures or organs that are adapted to produce the sex cells. Once these cells are produced, the organism
must have a method to allow the male sex cell to reach the female sex cells. This is brought about in
different ways by plants and animals. Once fertilisation has taken place, plants produce a seed which is
dispersed by various mechanisms. In humans, the embryo grows into a foetus in the mother’s uterus. The
parents of the child have to provide everything it needs to survive until it becomes independent.
This topic also includes issues such as puberty, sexually transmitted diseases and understanding the
myths that surround sex.
Common errors learners make
There are many myths that cloud young peoples’ understanding of puberty, pregnancy and sex. This
provides an opportunity for the learners to talk in a non-threatening environment about the things that
they do not understand or find confusing. The learners should be encouraged to ask questions but if they
are uncomfortable, writing questions anonymously on a piece of paper and placing them in a box is a
good alternative.
Resources for this topic
•
•
•
•
•
•
•
•
A blade; a flower, such as a petunia, plumbago, hibiscus or agapanthas
2 flat sheets of cotton wool about 5 cm by 5 cm per group
Some bean or maize seeds per group
A Petri dish, saucer or similar container per group
Water
1 spray bottle per group
Soil
1 ruler or measuring tape per group
Suggestions for additional resources
•
•
•
DVDs on sexual reproduction in plants and animals
Clinic brochures on contraceptives and sexually transmitted diseases
Library books
Starting off
Teaching guidelines
Introduce the topic by discussing what the learners already know about reproduction. Discuss both
asexual and sexual reproduction. Ask the learners to complete Activity 1 to find out what they know
about sexual reproduction.
Activity 1: Recall information about human reproduction
LB page 29
Answers
1.
2.
3.
4.
16
Reproduction is the process by which organisms make more organisms like themselves. Hence the
organisms are produced ‘again’.
Pollen
Fertilisation is the joining of a male and a female sex cell OR joinng of a sperm and an egg or ovum.
Eggs or ova
Term 1
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Unit 1: Sexual reproduction in angiosperms
Teaching guidelines
Discuss the structure of a flower, emphasising the male and female parts and the role played by all the
parts in reproduction. Explain what pollination is and how this is brought about in different types of
plants. Discuss the ways in which plants are specially adapted for different types of pollination.
Ensure that the learners understand the importance of seed dispersal. Discuss the various ways in
which fruits and seeds are adapted to ensure efficient seed dispersal.
Activity 2: Examine and identify the parts of a flower
LB page 30
Answers
Refer to Figure 2 on page 30 of the Learner’s Book. The learners’ drawings should be neat and have the
following labels: stamen, anther, filament, receptacle, peduncle, petal, stigma, style, ovary, pistil, sepal.
Activity 3: Recall the parts of a flower
LB page 31
Answers
1.
2.
a)
b)
c)
d)
e)
a)
b)
c)
d)
e)
Petals
Pistil
Ovules
Stigma
Sepals
Protects and encloses the other whorls while the flower is developing
Produces pollen
Carries the anther
Contains the ovule
Connects the stigma to the ovary
Activity 4: Identify adaptations of flowers for pollination
LB page 33
Answers
1.
2.
a)
b)
c)
a)
b)
c)
By insects
By wind
By birds
The flowers also have brightly coloured petals.
Large amounts of pollen are released into the air. They have long stigmas and filaments that
hang out of the flowers, exposing the stamens and stigmas to the wind.
The flowers have brightly coloured petals to attract birds. They are tubular in shape to suit the
beaks of birds.
Activity 5: Revise the process of fertilisation in angiosperms
LB page 35
Answers
1.
2.
a)
b)
a)
b)
4
5
The male sex cell fuses with the female sex cell.
A fertilised egg
Topic 3: Sexual reproduction
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3.
4.
c)
d)
a)
b)
c)
a)
b)
c)
Tissue that provides nutrition for the embryo
The reproductive structure produced by plants
Attracts insects and birds to the flower for pollination
Contains the male sex cells and is carried from the male part of the flower to the female part of
the flower
It is a sweet liquid that attracts insects and birds to the flower.
It forms the fruit.
It forms the seed.
The petals shrivel up and fall off.
Activity 6: Revise your knowledge of seed dispersal
LB page 37
Answers
1.
2.
3.
4.
5.
18
By means of fruit and seeds
• The flower stalks break off just above the surface of the ground. The wind rolls the whole flower.
As this happens, the seeds fall out onto the ground.
• The fruits grow on long, thin stems. The seeds are light and are shaken out when the wind blows.
• The seeds have wings to glide on the wind.
• The fruit and seeds have hairlike outgrowths to help them drift away from the parent plant.
Animals, water, self-dispersal
If the seeds of plants land next to the parent plant, there would have been too many of the same
plants competing for the same resources.
Enough water, warmth and mineral salts
Term 1
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FORMAL ASSESSMENT
Practical task: Grow a plant and observe its life cycle
LB page 38
Teaching guidelines
•
•
•
This activity is best done during the warmer months. Arrange the class into groups of three or four.
Try to ensure that the groups are chosen so that there is an even distribution of strong and weaker
learners.
The learners will grow bean or maize seeds. In order for the learners to be able to see the differences
in these plants, have half the class grow bean seeds and the other half grow maize seeds.
Ensure that the growing seedlings can be stored in a safe place that the learners will have access
to each day in order for them to make measurements and water their plants. Observations should
continue for as long as necessary to observe the full life cycle.
Assessment tool
1. and 2. The growth rate of seedlings will vary.
3. The root. It forms first to absorb water for the growing seedling.
(2)
4. The answer will depend on how fast each groups’ seed grows.
(1)
5. The learners’ answers will vary depending on how fast their leaves grew. The leaves will undergo
photosynthesis to produce food for the plant.
(2)
6. The cotyledons shrivel up and eventually fall off. They originally contained a food reserve which is
used by the seedling as it grows. As the food in the cotyledons is used up, the leaves take over the
production of food.
(2)
7. The learners’ graphs will vary depending on the results of the experiment. The graph should be
marked out of 9 according to the following table:
Marking criteria
Mark allocation
A full and detailed caption has been given
1 mark
The x-axis has been labelled with units
1 mark
The y-axis has been labelled with units
1 mark
An appropriate scale has been used on
the x-axis
1 mark
An appropriate scale has been used on
the y-axis
1 mark
The correct type of graph has been drawn
1 mark
The plotting of points
All points have been plotted correctly: 3 marks
4 to 6 points have been plotted correctly: 2 marks
1 to 3 points have been plotted correctly: 1 mark
(9)
10. The actual rate will depend on the results of the experiment, but it should be calculated using the
following formula:
final measurement
number of days = _____________ mm per day
(4)
Total: 20
Topic 3: Sexual reproduction
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Support for learners with barriers to learning
Separate the learners who are not disciplined into different groups. Give numbers to each learner in a
group and let them do the tasks as follows:
•
No. 1: Read the instructions.
•
No. 2: Moisten the cotton wool and set up the experiment.
•
No. 3: Draw up a table in which the results will be recorded.
The learners should take turns measuring and recording the results of their experiment.
Unit 2: Human Reproduction
Teaching guidelines
Begin the discussion on human reproduction by discussing puberty as this is familiar to the learners.
Explain what puberty is and the changes that occur in girls’ and boys’ bodies at this time. Study the male
and female reproductive organs and explain the role that each part plays in sexual reproduction. Discuss
the menstrual cycle and ensure that the learners understand the role that hormones play in this process.
The learners should understand that the purpose of sexual intercourse is to place the sperm in the top of
the female’s vagina to give it the best opportunity to swim to the egg. Ensure that the learners understand
the concepts of fertilisation, implantation and pregnancy.
Discuss contraception, how to prevent being infected with sexually transmitted diseases and the
myths that surround menstruation and sex.
Activity 7: Draw a timeline to record personal development
LB page 41
Answers
The learners should work in groups to discuss the developmental changes that are illustrated in the
timelines in their learner books. The answers to Question 3 will depend on each of the learner’s own
experiences.
Activity 8: Label and interpret diagrams of the human reproductive organs
LB page 43
Answers
1.
2.
3.
4.
a) 1: ovary
b) 4: vagina
c) 2: Fallopian tube/oviduct
1: ovary; 2: Fallopian tube; 3: uterus; 4: vagina
a) 3: testes
b) 2: urethra
1: sperm duct; 2: urethra; 3: testis; 4: scrotum
Activity 9: Revise the menstrual cycle
LB page 45
Answers
1.
2.
3.
20
The monthly series of changes in a female’s body in which ovulation and menstruation take place.
This indicates that she has started to ovulate (produce an egg) and is therefore capable of falling
pregnant.
The lining of the uterus, which has become thick in preparation for a pregnancy, is shed and leaves
the female’s body through the vagina.
Term 1
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4.
5.
6.
7.
8.
Menstruation is the bleeding that occurs as a result of the lining of the uterus being shed through the
vagina. Ovulation is the release of an egg cell or ovum from the ovary.
a) Days 1 to 5
b) Day 14
c) Days 12 to 17
d) Days 1 to 5
28 days
14 days
14 days
Activity 10: Discuss myths about menstruation and sex
LB page 49
Answers
1.
2.
3.
True statements:
•
A girl can fall pregnant before she has had her first period.
•
Boys’ higher levels of testosterone can make them more aggressive.
•
Condoms can protect both boys and girls from getting sexually transmitted diseases.
False statements:
•
If boys don’t have sex, the build-up of sperm becomes painful.
•
A girl will not fall pregnant if the boy withdraws his penis before he ejaculates.
•
There is absolutely no chance that a girl can fall pregnant if she has sex during her period.
The learners should discuss their lists with other learners.
The learners should discuss any other myths that they may know about menstruation and sex.
Support for this unit
Some DVDs that may be useful when teaching this section include:
•
Life, narrated by David Attenborough (BBC Earth)
•
Body Story, Part 4 Basic Instinct, Python Entertainment
•
The Human Body, presented by Robert Winston, BBC
Topic 3: Sexual reproduction
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Skills focus: Draw bar graphs and histograms
Activity 11: Practise drawing bar graphs and histograms
LB page 51
Answers
a)
b)
c)
d)
e)
f)
A bar graph. Each of the values belongs in a separate group.
Percentage of the population using the birth control method
Birth control method
Four. They should not be touching.
The highest number is 40. An appropriate scale could go up in units of ten.
Percentage of population
using the birth control
method
1.
50
40
30
20
10
0
Injection
Contraceptive
pill
Sterilisation
Other
methods
Birth control method
2.
a)
b)
c)
d)
The injection
IUD; diaphragm; rhythm method
Some people do not use any contraception.
9
10 × 1 000 = 90
TOPIC 3 REVISION
LB page 54
Science language activity
Answers
1.
a)
b)
c)
d)
2.
22
a)
b)
c)
d)
e)
f)
g)
h)
Sperm are the male sex cells; eggs are the female sex cells.
A stigma is the sticky structure found at the top of the pistil in flowers; the anther is the structure
found at the top of the stamen in flowers that produces pollen.
Ovulation is the release of an egg cell from the ovary; menstruation is the shedding of the lining
of the uterus through the vagina.
Implantation is when the ball of cells formed after fertilisation burrows into the lining of the
uterus; fertilisation is the fusion of the male sex cell and the female sex cell.
Petals
Ovary
Foetus
Pollinator
Germination
Contraceptive
Menstruation
Puberty
Term 1
9780636140905_plt_nat_g07_tg_eng_za.indb 22
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Test yourself
Answers
1.
a)
b)
c)
d)
2.
a)
b)
c)
d)
e)
4: pistil; 7: filament; 9: sepal
(3)
Produces pollen
(1)
Attracts birds and insects
(1)
Birds or animals can eat the seeds. The seeds can hook on to an animal’s fur. The seeds have
wings and can be blown by the wind. The seed pod can burst open and shoot the seeds out.
The seeds may float away in water. (Any three answers)
(3)
1: Fallopian tube; 3: foetus
(2)
The sperm are released into the top of the female’s body. The sperm swim up through the
uterus towards the Fallopian tubes. If an egg cell is present in the Fallopian tube, one of the
sperm cells fuses with it. This process is called fertilisation. The fertilised egg starts to divide
and moves down the Fallopian tube to the uterus. The ball of cells burrows into the lining of
the uterus and implantation occurs.
(4)
The placenta provides the baby with all the nutrients and oxygen that it needs to survive, as
well as removing all the wastes that the baby produces.
(2)
During pregnancy, the substances that a mother takes into her body can affect her baby. She
should eat healthily to ensure that the baby receives all the nutrients that it needs. She should
not take drugs or drink alcohol, as these may damage the developing baby.
(2)
Natural methods of contraception include the rhythm method and the withdrawal method,
neither of which are effective. Artificial methods of contraceptive include the male and female
condoms, the pill and the intra-uterine device. If used correctly, they are effective.
(2)
Total: 20
Topic 3: Sexual reproduction
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TOPIC 4: VARIATION
Topic overview
There are differences between species, for example a zebra is different from a horse. There are also
differences within a species. For example, although all zebras look very similar at first, on closer
inspection you will observe differences between them. These differences are called variations. Most
variations have no effect on an individual. However, some variations may be advantageous to an
individual. For example, the variation may help the organism survive better, which means that it
will be more likely to reproduce and pass on this favourable characteristic to its young. Over time,
the characteristic is passed on to more of the young within the population. Variations that are not
advantageous can make survival difficult, so an organism may not reproduce and the characteristic will
not be passed on. This topic links with Topic 1.
Common errors learners make
Some learners may think that variations that lead to adaptations happen because the animal or plant
‘wants them to occur’. Emphasise that variations are ‘mistakes’ that happen in the genes. They happen
by chance. Talk about what variation means and then ask the learners to write down a definition of
variation.
Resources for this topic
•
•
One ruler or measuring tape per group
Website for tongue rolling:
http://udel.edu/~mcdonald/mythtongueroll.html
http://www.biotopics.co.uk/genes/varn.html
Starting off
Teaching guidelines
Use the photograph in the Learner’s Book to introduce the topic. They must look very carefully to make
their own observations. Also get the learners to bring photos of certain animals they may have at home,
such as cats. Then allow them to compare the faces of the cats.
Activity 1: Identify variation in living things
LB page 55
Answers
1.
a)
2.
b)
a)
b)
24
They all have black and white stripes that run down the front of their faces, along their cheeks
and over their bodies.
The thickness of the stripes and the angles that they run along are different.
Everyone has a head with two eyes, two ears, a nose and a mouth. Everyone also has four limbs
and a trunk.
Learners differ in height and weight, have different eye, skin and hair colour, and differently
shaped facial features.
Term 1
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Unit 1: Variation exists within a species
Teaching guidelines
The skills that the learners will use in this topic are measuring and drawing, and interpreting graphs.
Revise measuring with the class. Explain to the learners that they must work in pairs to take each other’s
measurements. They need to stand up straight, next to a wall. They should remove their shoes. Use
measuring tape and ensure that it is held straight. Place a book or ruler on top of the learner’s head.
Where it touches the wall is the point that you should measure down to the floor.
Revise bar graphs with the learners. Refer to the Skills Focus on how to draw bar graphs and
histograms on page 50 of the Learner’s Book. Go through the different steps of drawing a bar graph
with the class. The axes must be drawn and labelled, and a heading for the graph must be provided. Many
learners struggle with the scale. Explain that the distances between each of the graduation marks must be
the same. The learners must also take note of the smallest and largest numbers that need to be included
on the graph. Explain to the class that once they have all the different heights, it will be difficult to make a
bar graph. For this reason, heights need to be grouped together in height ranges to make a histogram.
Activity 2: Describe variation
LB page 57
Answers
1.
2.
3.
4.
5.
a)
A species is a group of living things of the same type that can reproduce with one another to
make more individuals of the same species.
b) Variation refers to differences between organisms.
a) The answers here will vary and could include eye colour, height, straight or curly hair and skin
colour.
b) They are inherited from our parents.
Colour, size and shape of the rose
a) The colour of the hair, shape of eyes, shape of face.
b) Variations
c) Some variations make an animal easier to see. This makes it harder for the animal to catch food
if it is a predator and harder for it to hide from its enemies. The animal may not be able to get
enough food and may not survive and reproduce. A variation may cause an individual to become
sick more easily.
A characteristic in people that shows a range of variation is weight or height and one example of an
either/or characteristic is eye colour or gap between front teeth, or presence of an extra finger.
Topic 4: Variation
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Activity 3: Measure and collect information about height
LB page 58
Answers
3.
Here are some example heights that the class could record:
Name
Height (cm)
Name
Height
Steve
150
Jon
130
Nomsa
126
Jane
133
Marjorie
128
Max
132
Tim
127
Sipho
134
Tom
130
Josh
121
Tembela
136
Ray
140
Thandi
139
James
143
Vusi
135
Sally
140
Jen
139
Thandeka Kim
141
Mike
145
Lise
144
Amy
147
Lindewe
149
5.
6.
144
Yes, heights that are similar could be grouped together and then the number of people with that
height added up.
Here are some answers for a class:
Height
range 120–124
(cm)
125–129
130–134
135–139
140–144
145–149
Name
Nomsa (126)
Tom (130)
Tembela (136)
Ray (140)
Mike (145)
Marjorie (128)
Jon (130)
Thandi (139)
James (143)
Amy (147)
Tim (127)
Jane (133)
Vusi (135)
Sally (140)
Max (132)
Jen (139)
Sipho (134)
Dan (138)
Thandeka
(141)
Lindewe
(149)
Phumla (136)
Kim (144)
Nosipho (135)
Lise (144)
Josh (121)
150–
154
Steve
(150)
Emma (137)
Total
7.
•
•
•
•
1
3
5
8
6
3
1
Make sure that the histogram has the following components:
Label for x-axis: Height range (cm)
Data is plotted correctly on the graph. There should be no gaps between the bars of a histogram.
Label for y-axis: Number of Grade 7 learners
Heading: Number of learners with different height ranges in a Grade 7 class.
10. This table will be similar to the one in Question 3.
26
Term 1
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12. a) 135–139 cm
b) The graph has a bell shape.
13. Compare the graph for the learner’s heights with the graph showing adults heights.
a) The answers will vary, but the learners can categorise themselves as short, average height or tall.
b) Yes, for example, if the child is short, it is likely that his or her parents will also be grouped with
the shorter height range. There is a correlation.
c) There is a correlation between heights of family members and their children. This is because the
characteristic of height is an inherited characteristic and is passed down from the parents to the
children.
14. Measure the height of a larger number of Grade 7 learners and their parents; check that each of the
learners is born in the same year.
15. Is there a correlation between having blond hair and having blue eyes?
Activity 4: Analyse a graph of height
LB page 60
Answers
1.
a)
b)
c)
d)
e)
Bell-shaped
8
160–169 cm
Gradual
Inherited characteristic: gap between the front teeth/no gap; ear lobes attached to head/ear
lobes free
Environmental characteristic: tattoo; tan; dyed or bleached hair
Activity 5: Discuss careers
LB page 60
Answers
The answers will depend on the different careers that are discussed. The information is not meant to be
used for assessment, but rather to broaden the learners’ minds and to help them understand the different
careers that they have available to them. Here is some information that will be useful. Encourage the
learners to find out some information themselves to bring to class.
Careers in chemical industry including mining, the food industry, agriculture and
chemical engineering
•
•
•
•
Agriculture
Agricultural careers can be divided into different categories such as: Agribusiness management,
Agriscience, Packaging, Horticulture, Forestry, Food Science, and Nature conservation and Wild
game management.
Chemical engineering
Chemical engineers work mainly for the chemical and petrochemical industries. They use math,
physics and economics to solve practical problems. Chemical engineers do things such as make
designs and invent new processes, plan and operate facilities, develop new compounds such as
polymers, paper, dyes, drugs, plastics, fertilisers, foods, textiles, and chemicals. Chemical engineers
work out ways to make products from raw materials and ways to convert one material into another
useful type of material.
Mining
A metallurgical engineer is involved in the processing of ores to produce products such as metals.
A combination of processes, including physical processes, is used to separate metals or salts from
their ores. The valuable metals are separated and given further treatment such as smelting to reduce
them to the required metal. Metallurgists use high temperatures to extract metals and this dates
Topic 4: Variation
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2014/09/29 7:17 PM
back thousands of years. They are also involved in upgrading metal products so that the products
are stronger, harder and can be welded. Metallurgical engineers also improve other factors that are
important for metals in manufacture.
Food industry
Different careers in the food industry include:
— Food technologist - a person who applies science and engineering to the manufacturing process
of food development.
— Food scientist: a person who applies scientific and engineering principles in research,
development, product technology, quality control, packaging, processing and use of food.
— Food demonstrator: a person who demonstrates the preparation of a recipe in a shop, for
television or restaurants.
— Nutritionist: a person who develops programs on nutrition for individuals; may work in
weight-loss clinics.
•
Activity 6: Record information about tongue rolling
LB page 61
Answers
The following table provides the answers for Questions 1–6.
Tongue roller
Not a tongue roller
Total number
34
11
Total number of learners in the class
45
% in the class
76
Total number of immediate family tested
180
Number
150
30
%
83
17
7.
8.
9.
24
Make sure that the bar graph has the following components:
•
appropriate x-axis bars and labels
•
y-axis label: Percentage of people
•
appropriate y-axis scale
•
Heading: Percentage of tongue rollers and non-rollers among Grade 7 learners and immediate
family members
Yes, the correlation is very high. Most learners who are tongue rollers also have parents who are
tongue rollers.
Children whose parents are tongue rollers are more likely to also be tongue rollers. In the table above,
the percentage of learners who can roll their tongues is 76% and the percentage of adults (family
members) who can roll their tongues is 83%. From this, we can infer that tongue rolling is an
inherited characteristic.
Support for this unit
Many learners find graphs difficult. Reassure them that bar graphs are not difficult and that they are
simply pictures of information provided. Spend time with learners who are struggling with the drawing
of bar graphs by going through each step carefully. Help them to work out the scale for the y-axis. Create
some different results or create some results of people with different weights that they can draw as a bar
graph.
Extension for this unit
Learners can research other common variations between people, such as how earlobes are attached,
presence of a gap between front teeth or not, presence of a widow’s peak, or hair on knuckles. They can
find out how common each of these characteristics is and present their findings as bar graphs.
28
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TOPIC 4 REVISION
LB page 62
Science language activity
Answers
1.
a)
b)
c)
Inherited characteristic: features that are passed down from parents to their young, for example
height or eye colour
Variation: differences between organisms of the same species.
Inference: to draw conclusions based on evidence
Test yourself
Answers
1.
2.
3.
4.
a)
Total numbers of learners in the class is 45.
people = 87% of learners have a straight thumb.
(2)
b) He could examine the thumbs of more people, such as the whole grade.
(2)
c) Make sure that the learner’s bar graph is drawn correctly. Refer to pages 50–51 of the
Learner’s Book for guidelines on how to draw a bar graph.
(10)
Eye colour, gender, ability to roll the tongue. (Any two characteristics)
(2)
a) Most members of the class had the similar height ranges and few learners were very short
or very tall. This produced a bell-shaped graph.
(2)
b) Make sure that all variables were kept the same. For example, all class members were of the
same age. They could also record the data of males and females separately.
(2)
c) Height is a characteristic that is inherited from one’s parents. Learners who have tall parents
are likely to be tall.
(4)
d) It would help them to make clothing that will fit the population of Grade 7s correctly and so
increase their sales. The sizes of people change, for example, if their diet changes.
(2)
a) Tongue rolling
(1)
b) Fair hair
(1)
c) Test a larger sample of people
(2)
39
45
Total: 30
Topic 4: Variation
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TERM 1 PRACTICE TEST MEMORANDUM
LB page 63
1.
a)
b)
c)
d)
e)
C
A
B
B
D
(1)
(1)
(1)
(1)
(1)
2.
a)
b)
c)
d)
e)
Variable
Dicotyledon
Species
Hypothesis
Fertilisation
(1)
(1)
(1)
(1)
(1)
3.
a)
The first photograph shows a fish. It has scales, gills and fins. (Any one reason)
The whale is a mammal. It has lungs, gives birth to live young, suckles its young.
(Any one reason)
(4)
They have streamlined bodies to move through the water easily. They have fins for swimming.
Gills are used to absorb oxygen from water. (Any two reasons)
(2)
b)
4.
5.
6.
They produce seeds which can survive dry periods. They have waxy leaves that reduce water loss.
They have well-developed root systems to absorb as much water as possible.
a)
b)
c)
d)
a)
b)
c)
d)
1: ovary, 2: uterus, 3: vagina
1
2
Menstruation occurs when the layer of blood vesthe uterus is released through
the vagina.
(2)
(3)
(1)
(1)
(2)
Black
(1)
2
(1)
There should be a correlation (relationship) between the hair colour of the children and their
parents because hair colour is an inherited characteristic.
(2)
Variation is the difference between living things of the same species. Some types of variation,
such as height, eye colour and hair colour, can be inherited.
(1)
Total: 30
30
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TERM 2
Within Term 2, your Grade 7 learners will cover the following sections of content:
Strand
Topics and time allocation
Unit
LB page
Matter and
Materials
5 Properties of materials
Unit 1: Physical properties of materials
66
(7 hours)
Unit 2: Impact of the environment
76
6 Separating mixtures
Unit 1: Mixtures
80
(7 hours)
Unit 2: Methods of physical separation
82
Unit 3: Sorting and recycling materials
90
7 Acids, bases and neutrals
Unit 1: Tastes of substances
96
(7 hours)
Unit 2: Properties of acids, bases and
neutrals
98
Unit 3: Acid-base indicators
104
Unit 1: Arrangement of elements in the
Periodic Table
110
Unit 2: Properties of metals, semimetals
and non-metals
114
8 The Periodic Table of Elements
(7 hours)
TERM 2 ASSESSMENT
The following Formal Assessment Tasks will need to be completed in Term 2. You may use the examples
in this book for your learners, or you may want to develop your own.
Formal assessment
Mark allocation Learner’s book page
Teacher’s guide page
Practical task: Design and explain
the best ways to separate a
mixture
30
89
42
Term 2 Practice test
30
123
57
Term 2: Introduction
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TOPIC 5: PROPERTIES OF MATERIALS
Topic overview
This topic explores the properties of materials and the suitability of those materials for various uses. The
properties explored are strength, flexibility, boiling and melting points, and electrical and thermal (heat)
conductivity. Emphasise the fact that when a liquid heats up, we can measure its temperature increase.
However, when it starts to boil, the temperature no longer increases. It remains at that boiling point
(approximately100 °C in the case of water) until it has evaporated. The production, use and disposal of
materials have a significant impact on the environment. We also explore the advantages and disadvantages
of using plastic.
Common errors learners make
The main conceptual error that learners make is thinking that boiling and melting points are fixed
numbers. You will notice in this topic that we are careful to say ‘approximately 100 °C’, for example (the
actual temperature depends on the liquid). This is because pressure differences and slight impurities affect
boiling and melting temperatures. Learners also think that a liquid will get hotter when it is boiling. This
is not true. People waste a lot of energy trying to make sure the water being boiled is really hot. They are
also wasting their time!
Resources for this topic
•
•
•
•
Strips of paper, wax paper, newspaper, plastic shopping packet, aluminium foil, plastic shopping
packet, stones (per group)
Some electrical wires, a battery, a torch bulb, a collection of objects to test their electrical
conductivity (per group)
A glass beaker or tin, a tripod, a gauze mat, water, a thermometer, a Bunsen burner or spirit burner, a
watch to time three-minute intervals (per group)
Three glass jars or metal tins; three thermometers; three different materials such as aluminium foil,
newspaper, cotton wool, fabric and elastic bands; sticky tape (per group)
Starting off
Activity 1: Investigate the properties of materials around you
LB page 65
Answers
1.
2.
3.
32
The learners must list the items shown in Figures 1–3.
a) For example, wood for desks, glass for windows, clay for bricks, concrete for floors, plastic for
pen holders, fabric for clothing, and so on
b) Wood: strong, smooth (when sanded), easily made into the right shape, inexpensive
Glass: transparent, waterproof
Clay: dries very hard, strong, has compressive strength
Concrete: dries very hard, strong, has compressive strength, can be made very smooth on top
Plastic: waterproof, easy to clean, can be made to look attractive
Fabric: soft, flexible, good insulation properties
Learners’ answers will vary.
Term 2
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Unit 1: Physical properties of materials
Teaching guidelines
This is a very interesting topic that provides lots of opportunity for practical activities and experience, as
well as discussion about properties of materials and suitability.
Activity 2: Investigate and compare the strength of materials
LB page 66
Answers
3.–5. The answers that the learners get will depend on the materials and size of the stones used as weights.
6. The learners should find that newspaper breaks easily, with the smallest number of stones, while
plastic is the strongest. The plastic might even be stronger than the strength of the tape adhesive
holding the strip to the desk. The discussion should be around the relative strengths of materials and
why they differ, what properties lead to these differences, and also the fairness of the testing
7. Tensile
Activity 3: Select a material to wrap food in
LB page 67
Answers
1.
2.
3.
Clingwrap, wax wrap, paper, plywood
Plywood: not flexible, not hygienic; paper: is flexible, but is not waterproof and not hygienic;
wax wrap: is flexible, waterproof and hygienic, but needs to be wrapped carefully otherwise it
comes apart easily; clingwrap: flexible, waterproof and hygienic, transparent, sticks to itself
The most suitable material is clingwrap. All of its relevant properties have been listed above.
Activity 4: Read about the boiling and melting points of different materials
LB page 68
Answers
1.
2.
3.
a)
b)
Lead, silver, gold, salt, copper, ethanol
Lead melts at a low temperature so it can be used in electrical fuses. If the wire/circuit overheats,
the fuse will melt before the wiring does.
Both silver and gold can be used for making jewellery because they melt at a moderately low
temperature. This makes it possible to work with them using equipment that does not have to
reach very high temperatures and so does not have to be very expensive and very hot.
Salt melts at a moderately low temperature, and so it can be used to store heat and be pumped in
liquid form from one place to another. This is why it is suitable to use as energy to heat water in boilers.
a) Water remains liquid at room temperature and across the range of temperatures that humans
spend most of their time in. This is important because we need to drink water to stay alive, and
if it was solid at normal room temperature, this would be a problem. Water can also be frozen
into ice blocks, which is useful for cooling down drinks.
b) Candle wax melts and becomes a liquid fuel for the candle flame. When we blow out the flame, it
solidifies and can be stored safely without a mess. This makes it very convenient to use for light.
Candle wax can also be used to seal things like envelopes as it can be melted onto the envelope
and then left to harden.
d) Steel does not melt at low temperatures, and so we can confidently use it on a hot stove to cook
food in.
Tungsten; it boils at 5 660 °C. Tungsten is also known as Wolfram and its chemical symbol is W for
this reason.
Topic 5: Properties of materials
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Activity 5: Test materials for electrical conductivity
LB page 69
Answers
The answers will depend on the objects selected. You will need to guide and assist. Metal objects will
conduct electricity.
Activity 6: Test thermal properties of materials
LB page 70
Answers
1.
2.
a) Copper
b) Iron
Copper has the best thermal conductivity properties, then aluminium, and lastly iron.
Activity 7: Investigate what happens when water reaches its boiling point
LB page 71
Answers
7.
The learners should notice that their graphs go steadily upwards from the starting temperature to
close to 100 °C. (This will be slightly lower at higher altitudes, as water boils below 100 °C the higher
you are above sea level.) From there, the graph should level out and not increase any further while the
water is boiling. This happens because all the energy being supplied is being used to change the liquid
into a gas. A liquid will continue boiling at the same temperature until it has evaporated.
Activity 8: Identify factors that influence the choice of materials
LB page 72
Answers
1.
2.
Learners’ own answers and discussions.
Factors include cost, colour, aesthetics or design and appearance.
Support for this unit
There are lots of practical activities that the learners can do in groups. Make sure you prepare yourself
and the materials carefully so you know exactly what to do. Use good classroom management techniques.
Support for learners with barriers to learning
Some learners never get a chance to handle apparatus during practicals because they are shy or lack
confidence. This is a barrier to learning that should help them overcome. Make sure that all the learners
get a chance to contribute to the activities, especially those who are not very confident. Girls also can
be pushed aside in situations like this. Make sure that all learners understand how to work together and
respectfully.
Skills focus: Draw line graphs
Teaching guidelines
Many of your learners will not have drawn a graph before. Make sure you discuss this with an experienced
Mathematics teacher and work out a way of combining the development of this skill in both subjects.
34
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Activity 9: Practise drawing a line graph
LB page 73
Answers
1.
Make sure that the learner’s graphs follow the guidelines listed on page 73 of the Learner’s Book.
Skills focus: Design a fair test
Teaching guidelines
The main point here is about the requirements of a fair test and how to design one. You could use the
example of a sprinting race. Everyone has to start and end the race at the same place, and everyone has
to run the same course. The only thing that is different is the runners themselves. We call these things
variables. Some are held constant and others are varied.
Activity 10: Practise designing a fair test
LB page 75
Answers
2.
3.
4.
5.
The size of the jars; the way they are wrapped; the starting temperature of the water
Newspaper, aluminium foil, elastic bands (however, this order may differ depending on the specific
qualities of the materials you use).
As in question 3.
Newspaper or aluminium foil, depending on the results of the specific test. Note: Ideally you would
line the flask with newspaper and cover that with aluminium foil. Discuss this with the learners and
see what they think. As an extension, they could try this and see how the result differs.
Unit 2: Impact on the environment
Activity 11: Read and write about how a material is produced and what its impact
is on the environment
LB page 76
Answers
1.
2.
3.
Plastic products are useful because they are inexpensive, strong, lightweight, and resistant to being
degraded by chemicals, sunlight and bacteria. Plastics can replace natural materials like ivory and
wood. They help make cars and aeroplanes lighter, and thus more fuel-efficient. Their heat-insulating
properties help save a lot of energy for heating or cooling.
Plastic is harmful to the environment because it causes pollution, uses up fossil fuels, lasts a long
time, but spends most of that time as waste or in landfill sites. It contains harmful chemicals, it can
enter the oceans and be swallowed by marine animals, it can injure or poison wildlife, and it can
pollute groundwater.
Manufacture: Plastics are made using oil. This causes pollution and releases pollutants into the air.
Use: Plastics have potentially harmful chemicals in them and these have health impacts.
Disposal: Plastics last a long time, and so they remain in ecosystems for long periods of time, causing
pollution and injuring marine life.
Support for this unit
This unit requires a lot of reading, comprehending and writing. Many learners have difficulty with this, so
make sure you explain clearly what they must do. You can also go through the material with them.
Topic 5: Properties of materials
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Support for learners with barriers to learning
Some learners have difficulty reading and comprehending information. As suggested above, make sure
these learners understand what they must do and the content they are reading.
TOPIC 5 REVISION
LB page 78
Science language activity
Answers
We use materials like steel to make pots, because we know they are not going to melt when we heat them
to cook something. We would not use ice to make a pot. Sometimes, we select certain materials specifically
for their melting or boiling temperature. For example, fuses in electrical circuits are made from materials
such as lead, which that melts at a low temperature. This protects the more expensive components in the
circuit and can even prevent fires.
Test yourself
Answers
1.
2.
Tensile strength and compressive strength.
a) Ladder made of rubber: it is bendy/flexible and not strong enough; knife made of glass:
it could shatter; bucket made of wire mesh: water will fall through the holes of the mesh;
lamppost made of cardboard: it will get wet and fall down; soccer ball made of iron: it is
too hard and heavy to play with and can hurt people if they kick it
b)
Object
Property that material must
have
(2)
(5)
Suitable material
Ladder
Strength, inflexibility, not too
heavy
Wood, aluminium
Knife
Ability to be sharpened
High-grade steel
Bucket
Waterproof sides, resistant to rust
Galvanised iron, steel
Lamppost
Water-resistant, rigid, strong
Steel, wood
Soccer ball
Can be inflated, has flexible sides,
not too heavy
Leather, plastic
(10)
3.
4.
5.
a) The temperature increases until the liquid reaches boiling point, at which point it remains
constant.
b) A straight line
c) It stays constant.
Change the material being tested; keep the size/thickness of the material and the strength of
the electric current the same
Benefits: it is cheap, can be made into many shapes and objects, has good thermal properties;
environmental impacts: it causes pollution, stays as waste for a long time, can injure marine
animals, contains harmful chemicals
(2)
(1)
(1)
(3)
(6)
Total: 30
36
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TOPIC 6: SEPARATING MIXTURES
Topic overview
This topic is about the different methods that we can use to separate mixtures. The content of this topic
has been designed so that learners first understand what a mixture is and then work through a series of
practical activities where they separate mixtures for themselves using different methods. The method used
to separate a mixture will be determined by the properties of the constituents of the mixture. Drawing a
summary table of the different methods will help learners to remember the different methods.
Common errors learners make
Many learners do not understand that the particle pictures represent the little particles that make up a
substance. They also struggle to identify mixtures from pure substances. For example, they may think that
a particle picture of a compound is a mixture because there are two or more different particles. Point out
that because each of the ‘units’ that represents the particles making up the substance are the same, this
means that the substance is not a mixture.
Resources for this topic
•
•
•
•
•
•
•
Sieves (one per group)
Filter funnel, filter paper, retort ring, retort stand and clamp, two beakers, jar or beaker with a
mixture of sand and water – for each group.
A mixture of sand and iron filings or paper clips containing iron, a magnet for each group.
Salt, water, saucer or evaporating dish for each group
Liebig condenser, salt, water, flat-bottomed flask, Bunsen burner or spirit burner, rubber tubing,
distillation flask with stopper and thermometer for one class demonstration (you can make your own
Liebig condenser if one is not available – see below)
A black felt-tip pen, koki or ballpoint pen, strips of white paper, glass jar, methylated spirits, pencil,
sticky tape for each group
Sand, iron filings, beads, salt, ethanol, water, tripod with gauze, Bunsen burner, filter funnel, filter
paper, two beakers
Suggestions for additional resources
Instead of using a filter funnel and stand, you can make your own filter funnel from an empty plastic
cooldrink bottle.
Liebig condensers are expensive, and so your school may not have one. In this case, you can get the
learners to design their own using these materials: Pyrex test tube, rubber stopper, delivery tube or plastic
tubing, test tube, beaker containing cold water, Bunsen burner, damp cloth or damp paper towel, a retort
stand and clamp for each group. If you do not have Bunsen burners, use spirit burners or candles.
Topic 6: Seperating mixtures
9780636140905_plt_nat_g07_tg_eng_za.indb 37
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Starting off
Teaching guidelines
The aim of this first activity is to find out what learners know about mixtures, and to explain to them that
they use methods of separating mixtures in their everyday lives. You could bring some kitchen tools such
as sieves, tea strainers, tea bags and egg separators to show the learners.
Activity 1: Identify methods of separation
LB page 79
Answers
1.
2.
3.
a)
He could pick them out by hand (hand sorting). The raisins are large in size and dark in colour.
They are larger and darker than flour particles.
b) Separation using a sieve. The mixture could be passed through a sieve and the raisins would
remain in the sieve while the rest of the cake mixture would pass through. The raisins could also
be separated by hand sorting as they are large and easy to see in the mixture.
An egg separator is used to separate the yolk from the egg white. A slotted spoon can be used to
remove cooked pasta from a pot of boiling water.
a) Not a mixture
b) Mixture
c) Mixture
d) Mixture
e) Mixture
f) Not a mixture
g) Not a mixture
Unit 1: Mixtures
Teaching guidelines
Explain to the learners what a mixture is. Explain that substances are made up of particles that are called
atoms, and they will learn about this in Grade 8. For this level, it is sufficient that learners understand that
substances are made up of little parts that we cannot see called particles. Explain that different substances
have different particles. We can use particle pictures to help us understand what a mixture is.
Activity 2: Identify mixtures in diagrams
LB page 81
Answers
1.
2.
a)
b)
c)
d)
a)
b)
c)
d)
It is a mixture because the particles are not all the same
It is a mixture because the particles are all the same
It is a mixture because the particles are not all the same
It is a mixture because the particles are not all the same
Mixture
Not a mixture
Not a mixture
Mixture
Support for this unit
Draw examples of particle pictures and ask learners to identify whether they are mixtures or not.
Extension for this unit
Learners can design their own particle pictures and you can use these as extra practice for any members
of the class having any difficulties.
38
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Unit 2: Methods of physical separation
Teaching guidelines
This is a practical section of the curriculum. It is important that every learner has the opportunity to use
the apparatus, as this will help them to understand the concepts. Learners will need to work in groups for
most of the activities, but check that all the learners are involved and that they do not sit back and let the
same learners do every activity.
Before each activity, ensure that you have sufficient apparatus for each group. To save time, you could
assign each member of the class to a group before the lesson. Explain to the whole class that they must
tidy their work space before the end of the lesson and before they can leave the classroom. Also, at the
beginning of each lesson, pick one group to help to tidy the classroom just before the end of the lesson.
Learners need to be able to use a thermometer and take readings from a thermometer. Explain that
they should shake the thermometer first and then place the bulb of the thermometer in the substance.
Make sure that they have their eyes level with the level of the mercury or red alcohol to prevent inaccurate
readings. Tell the learners that they must take the reading from the bottom of the meniscus. The meniscus
is the curved surface of the mercury or the red alcohol.
Activity 3: Separate a mixture of sand and water
LB page 83
Answers
1.
2.
3.
4.
The sand remains behind in the filter paper, and the water passes through the filter paper and collects
in the beaker or glass jar.
The mixture was separated using filtration. Filter paper was folded into half and then into quarters.
It was opened into a cone and placed in the filter funnel. The filter funnel was placed in a beaker or
bottom of a disposable water bottle. The mixture was poured slowly into the filter funnel.
A mixture of sand and water can be separated using filtration. The particles have different sizes so the
water particles are small enough to pass through the filter paper. The sand particles are too large to
pass through the holes in the filter paper and are trapped by the paper.
Filtering is used when making tea and filter coffee. Traditional beer is also filtered with a special
basket to remove large particles. When making cream cheese, the sour milk is placed in a muslin bag
and the liquid (whey) is filtered out leaving the curd behind, which is the cream cheese.
Activity 4: Write about wetlands as natural filters
LB page 83
Answers
1.
2.
3.
Filtration: a method used to separate a solid from a liquid because of a difference in size of the
particles;
Insoluble: a solid that does not dissolve in a liquid.
Water carrying suspended particles of sand flows into a wetland where there are plants with roots.
The water is slowed down here because of the roots. The sand particles get stuck in the roots and the
water continues to pass through.
Wetlands act as filters, removing the sand particles and so reducing soil erosion. They also slow down
the movement of water, which reduces the risk of floods. And they also help to clean water as it
passes through the wetland.
Topic 6: Seperating mixtures
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Activity 5: Separate a mixture using a magnet
LB page 84
Answers
4.
5.
6.
The iron filings were attracted to the magnet but the sand was not.
Steel is magnetic while sand is not. They can be separated using this difference in their properties.
For example: Add water to the mixture and then swirl it around so that the sand particles that are less
dense move to the surface and the denser iron remains at the bottom of the container. Filter the iron
and water mixture to get the iron particles. This method is more difficult and takes longer, and so is
not an improvement. Sieving could also be used but will not separate all of the sand and iron filings.
Activity 6: Separate a solution of water and salt
LB page 85
Answers
4.
a) Solid, soluble in water, white, crystalline
b) Liquid, colourless, has no odour or taste
c) Liquid, colourless, salty taste
5. Learners’ answers will vary.
6. The level of the mixture decreases until eventually all the water has evaporated and only crystals of
salt remain.
7. The answers will vary, but will be in the range of a few hours to a day, depending on the air
temperature.
8. Heat the mixture with a Bunsen burner or a candle.
9. Evaporation can be used to separate a mixture of salt and water.
10. In very hot areas along the coastline, people can spread sea water into shallow pans. The Sun’s energy
evaporates the water, leaving salt behind. This simple method can be used to provide some jobs. For
example, the salt that is collected can be sold.
11. Broken glass looks a lot like crystals of salt and if any bits of broken glass were to find their way into
the salt, they would be very difficult to remove. If any salt containing bits of glass was sold, it could
affect people’s health and people would not want to buy that salt.
Activity 7: Observe distillation
LB page 86
Answers
1.
2.
3.
4.
5.
40
•
•
•
•
The mixture was placed in the distillation flask.
The thermometer and stopper were placed in the mouth of the flask.
The distillation flask was clamped to the clamp stand.
The condenser was clamped to the stand and the upper rubber tubing was placed in a basin so
that water can run into the basin. The lower rubber tubing is attached to a tap.
•
A beaker was placed at the open end of the condenser.
•
The Bunsen burner was lit and used to gently heat the bottom of the flask.
•
The temperature of the liquid was kept close to 100 °C.
•
The tap was turned on so that water moves continuously through the outer glass tube of the
condenser and drains out through the upper rubber tubing.
This is to cool the water vapour so that it condenses.
100 °C, because this is the temperature at which water boils.
The water evaporates when the particles gain enough energy. The water vapour rises in the flask
and enters the inner glass tube of the condenser. Water that is passed through the outer tube of the
condenser cools the water vapour so that it condenses and collects in the beaker.
The salt remains at the bottom of the distillation flask.
Term 2
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6.
A solute and the solvent can be collected by distillation.
Activity 8: Separate the pigments in ink by chromatography
LB page 87
Answers
6.
7.
8.
a)
The answer will vary depending on the type of ink that is used, but you can expect these colours:
brown, red, blue, green and yellow.
b) Blue
c) Yellow, blue/green, violet, red
Black ink is a mixture of five different colours of ink: brown, red, blue, green and yellow. It can be
separated by chromatography because each colour travels through paper at different speeds.
The investigation could be repeated using different colours of ball point pen such as blue. You could
also use different solvents, for example, you could use water instead of methylated spirits and a watersoluble koki instead of the ballpoint ink.
Support for this unit
For learners who struggle with all the different methods of separation, draw a table that they can fill in to
summarise all of the activities. Here is an example:
Separating method Description of mixture
1. Hand sorting
Beans and buttons
Differences between the parts
of the mixture
Objects of different sizes, colours
or shapes that can be seen
Apparatus needed
None
2. Sieving
Extension for this unit
Learners can design their own apparatus that they can use to separate mixtures. For example, ask them to
design a filter funnel. Or, they could design a Liebig condenser that could be used to separate salt water
using solar energy.
Topic 6: Separating mixtures
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FORMAL ASSESSMENT
Practical task: Design and explain the best ways to separate
a mixture
LB page 89
Teaching guidelines
For this activity, learners will need to write down how they plan to separate their mixture. They must do
this on their own. If you do not have enough materials for each individual, allow each person to write
down their answers to Step 3 on their own. They can then work in groups to do the practical. They must,
however, hand in their own written report of their findings.
You will need to collect all the apparatus required for the activity beforehand. Set up as many work
stations as you can around the classroom so that no time is wasted during class time.
Assessment tool
2.
3.
4.
5.
Hand sorting, magnetism, filtering, distillation
(4)
The following methods could be used in this order. Note that a different method could be used as
long as it is feasible.
•
Step 1: Hand sorting to remove the beads
•
Step 2: Use a magnet to separate the magnetic iron filings from the rest of the components.
•
Step 3: Filtering to remove the insoluble sand.
•
Step 4: Distillation to separate and capture the water and the salt.
•
Allocate one mark for method of separation and one mark for the correct order so that each
component of the mixture was successfully captured.
(5)
Pick out the large beads by hand. They are large enough to be seen. Use a magnet to attract the iron
filings. Only the iron filings are magnetic. Iron filings can then be collected in a beaker. Place the
rest of the mixture in a filter funnel lined with filter paper. The sand will separate from the mixture
because the particles have different sizes.The salt water can be separated by evaporation, but the
water is lost. The salt water is placed in the sun and the water evaporates leaving the salt crystals
behind. The water could be captured after condensation if distillation is used.
Award 3 marks for each method described.
Mark the learners’ diagrams by referring to the labelled figures in the Learner’s Book, for example,
Figure 17.
(12)
Use the following sliding scale based on the success of the separation methods used.
Criteria
5
4
3
2
1
All five parts of the
mixture separated
and collected; learner
acknowledges this;
the water vapour
could be collected by
distillation
Four substances
separated:
salt and water
separated by
evaporation and
the water was not
captured
Three
substances
separated;
sand separated
by filtration
Two
substances
separated:
iron separated
using a magnet
One substance
separated:
beads were
separated by
hand sorting
(5)
6.
a)
b)
The method was successful as all of the substances were separated. Very little of each of the
substances in the mixture were lost.
(2)
Problems may have arisen if the filter paper breaks – learners must make sure that the mixture
is poured in slowly and carefully. The temperature in the distillation flask needs to be carefully
monitored – learners should take care to watch the thermometer and to remove the flame
when necessary.
(2)
2
42
[30 × 3 = 20]
Total: 20
Term 2
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Support for learners with barriers to learning
Many learners will struggle to use the thermometer correctly. Make sure that each learner in the class is
given the opportunity to practice using the thermometer. Explain that the bulb is the part that needs to be
placed in the substance, the temperature of which they are measuring. Then, explain what the graduation
marks mean so that learners can work out the reading. Draw simple diagrams of thermometers with
different levels so that learners can practice reading the temperature.
Unit 3: Sorting and recycling materials
Teaching guidelines
This unit makes a link between separating methods, and the environment and recycling. Recycling is very
important as so many people throw their rubbish away and are too lazy to reuse or recycle it. In South
Africa, not enough is done about recycling. Encourage learners to be actively involved in recycling, both
at school and at home. Invite guest speakers to talk to the learners about recycling, and if you do not have
a recycling system at your school, start one – no matter how small.
Here are some useful links:
•
www.theglassrecyclingcompany.co.za
•
www.recycling.co.za
•
http://saaea.blogspot.com/2009/12/recycling-organic-waste.html
•
http://treevolution.co.za/guide-to-recycling-in-sa/
Activity 9: Investigate recycling at your school
LB page 92
Answers
1.
2.
3.
4.
5.
Learners’ answers will vary.
Collect the names and contact details of as many organisations as possible that deal with recycling of
waste. Contact organisations that deal with glass, paper, metal and plastic recycling.
Find out if these companies will bring recycling banks to the school property. Is there space on the
school grounds to store these recycling banks? How often will waste collectors come to collect the
waste? How much does the waste sell for per kilogram?
The learners’ plans must answer the following questions and follow procedure:
• Will you collect all of the different types of waste? If only specific types of waste will be collected,
the learners should name them. Include all of the information that you have researched about
the different organisations – will they deliver a water bank? Will they collect weekly or biweekly?
What will the funds raised be used for?
• Who will be the contact person? Will a class or teacher be nominated?
• Meet with the principal, a parent representative and your nominated teacher to explain your plan
and to ask for permission to carry it out.
• Consider how you will inform the rest of the school. How will you capture their attention? When
will you speak to the school?
Present your plan to the class. Vote for the best plan or a combination of the best ideas from
different plans. Put your ideas into action – after a month or so, consider inviting guests from the
municipality to show them how you are recycling wastes. Perhaps recycling on a wider scale could
be arranged in the community. Also try to involve the parents in the community so that the learners
bring waste from home that can be recycled.
Topic 6: Separating mixtures
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Activity 10: Discuss careers in chemistry, mining and waste management
LB page 93
Answers
This activity is not for assessment. The aim is to get learners to consider different career possibilities. Have
a class discussion about these careers and use the information below to give learners an idea of different
careers that are linked to separating substances. You could ask each learner to do some research on one
career that they find interesting, and which is linked to chemistry and separating mixtures. Also consider
inviting any parents involved in these careers to give a talk at the school.
•
Chemistry: There are many different careers in chemistry. One of these is a forensic chemist. They
analyse evidence brought in from a crime scene. They run tests on things such as urine, blood, paint
and hair samples. Skills that a forensic chemist requires include laboratory work, and the ability to
use tools from different areas of knowledge such as chemistry, biology, materials science and genetics.
They need to be good at public speaking as they have to present evidence in court.
•
Mining: A metallurgical engineer is involved in processing ores to produce products such as metals. A
combination of processes, including physical processes, is used to separate metals or salts from their
ores. The valuable metals are separated and treated further, for example, smelting, to reduce themto
the required metal. Metallurgists use high temperatures to extract metals and this process dates back
thousands of years. They are also involved in upgrading metal products so that they are stronger,
harder and can be welded, as well as other factors that are important for metals in manufacture.
•
Waste management: A person involved in waste management would be involved in many different
processes, for example, collecting, transporting, processing, recycling, disposing and monitoring
waste. Waste management focuses on reducing the effect of waste produced by human activity on
health and the environment. Skills that would be useful include organisational skills computer skills
and knowledge of waste and its effect on health and the environment.
Support for this unit
Ask learners to list materials that can be recycled and those that cannot be recycled. They can design
posters to illustrate what can be collected for recycling and materials that need to be sent to land fill sites.
Extension for this unit
Learners who are very keen about recycling can help to manage and encourage a recycling scheme at the
school. Make sure that learners are involved, but do check their activities.
44
Term 2
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TOPIC 6 REVISION
LB page 94
Science language activity
Answers
1.
2.
A mixture consists of two or more different substances. It has the following properties: the
constituents can be mixed in any quantity, they can easily be separated using physical methods and
the constituents keep their own properties.
Hand sorting: a mixture in which the constituents are of different size, shape or colour and large
enough to be seen can be separated by hand
Sieving: to separate two solids with particles of different sizes
Filtration: used to separate a liquid and an insoluble solid
Magnet: separates a magnetic substance from a non-magnetic substance
Evaporation: used to separate a solid that dissolves in a liquid – only the solid is captured
Distillation: uses evaporation and condensation to separate a soluble solid or it can be used to
separate a mixture of two liquids – each constituent will have a different boiling point
Chromatography: process used to separate different pigments in which some pigments dissolve in a
solvent more easily than others.
Test yourself
Answers
1.
2
3.
4.
5.
a)
Chromatography: the different colours or dyes in the petals will travel at different speeds through
the paper.
b) Magnetism: one part is magnetic and the other is not. OR Filtration: the iron filings will be
trapped in the filter paper and the water will not.
c) Distillation: the two liquids have different boiling points.
d) Hand sorting: the different parts of the mixture have different shapes and colours.
(8)
Separate a mixture of salt and pepper by adding water to dissolve the salt. Then filter the solution.
This will remove the pepper, which is not soluble in water. The particles of pepper are too small to
pan through the holes in the filter paper. Then evaporate the salt solution to obtain pure salt.
(5)
a) Blue
(1)
b) Alcohol
(1)
c) Brown
(1)
d) Pencil is not soluble in alcohol. If ink was used, it would dissolve and interfere with the results. (2)
e) Chromatography
(1)
a) All the variables will be controlled and only one will be changed.
(2)
b) The volume of the solvent, the temperature of the solvent (any one)
(1)
c) The different solvents
(1)
d) The amount that the green chemical in plant leaves will dissolve. The colours will need to be
compared. The darker the colour is, the better the solvent.
(3)
There is a finite amount of materials on Earth, and once they are used there will be no more.
People need to reduce their use of resources and start to recycle materials. This will save energy,
water and resources. It means less waste is produced and so landfill sites do not get filled as quickly. (4)
Total: 30
Topic 6: Separating mixtures
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TOPIC 7: ACIDS, BASES AND NEUTRALS
Topic overview
This topic starts by introducing acids, bases and neutrals. It then moves on to discuss the four different
tastes the tongue can sense. Learners test and describe the tastes of some common foods and substances.
They then learn about the properties of acids, bases and neutrals. Learners use litmus indicators to test for
acids, bases and neutrals to see how the colour of the litmus changes. Then test some household chemicals
and foods with litmus indicator to see whether they are acids, bases or neutrals.
Common errors learners make
Learners often think it is sufficient to test a substance with only one colour of litmus. They do not
understand why it is necessary to test with both red and blue litmus. Show them that in a neutral solution,
red litmus stays red and blue litmus stays blue. If, for example, you test a chemical with red litmus and it
stays red, it could be an acidic or neutral substance. You then need to test it with blue litmus as well to
eliminate one of the options.
Resources for this topic
•
•
•
•
•
Orange juice, bicarbonate of soda (baking soda), vinegar, milk of magnesia, lemon juice, salt milk, a
fizzy drink, a drinking straw each (per group)
Hydrochloric acid, white vinegar, magnesium metal, two test tubes, safety glasses each (per group)
Red and blue litmus paper, acids like hydrochloric acid and vinegar, bases like sodium hydroxide
solution and soap, neutrals like water and salt solution (per group)
Red litmus paper, blue litmus paper, glass containers, a drinking straw each, common beverages such
as water, tea, rooibos, milk, fruit juices and fizzy drinks
Red litmus paper, blue litmus paper, glass containers, household substances such as vinegar, tartaric
acid, aspirin, antacids, shampoo, soap, bicarbonate of soda, salt water, sugar water, liquid soap and
lemon
Starting off
Activity 1: Find out what you know about acids and bases
LB page 95
Answers
1.
2.
46
a)
b)
c)
d)
a)
b)
It preserves the lemons (keeps them fresh for longer).
Sour
Acid
Acidic
Bitter and soapy
Learners’ own ideas, for example, sweets are sweet, coffee is bitter, vinegar is sour, and salt on
food makes it taste salty.
Term 2
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Unit 1: Tastes of substances
Teaching guidelines
First ask learners to describe different tastes. They may come up with descriptions other than the four
main tastes (salty, sweet, sour and bitter). Explain the survival advantage of being able to distinguish
between these tastes, for example, selecting a ripe apple, which usually tastes sweet, but discarding an
unripe one, which tastes sour. Remind the learners that not all substances are safe to taste.
Activity 2: Describe the taste of substances
LB page 96
Answers
1. and 2.
Substance
Taste
Feel
Orange juice
Sour
Soft
Bicarbonate of soda
Bitter
Slippery
Vinegar
Sour
Rough
Milk of magnesia
Bitter
Slippery
Lemon juice
Sour
Soft
Salt
Salty
Rough
Milk
Slightly sour
Slippery
Fizzy cooldrink
Sour
Rough
Unit 2: Properties of acids, bases and neutrals
Teaching guidelines
Explain to learners that the acids in food are not dangerous, and so we can taste and feel them to find out
what their properties are. However, some other acids are dangerous and corrosive. Bases are used in most
cleaning products. Show learners the difference between a soluble base and an insoluble base to explain
what an alkali is. As a base is the opposite of an acid, you can add a base to an acid to make a neutral
substance.
Activity 3: Identify acids
LB page 98
Answers
1.
Orange juice, vinegar, lemon juice, fizzy drink; they all taste sour.
Topic 7: Acids, bases and neutrals
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2014/09/29 7:17 PM
Activity 4: Differentiate between a strong acid and a weak acid
LB page 100
Answers
1. and 2.
Acid used
Observation
Magnesium in hydrochloric acid
Fizzes vigorously; heat and gas are given off
Magnesium in white vinegar
Fizzes slowly; small bubbles of gas are given off
3.
4.
Hydrochloric acid
The magnesium reacted much more vigorously with the hydrochloric acid than with the vinegar.
Activity 5: Identify bases
LB page 101
Answers
1.
Bicarbonate of soda, milk of magnesia: they all taste bitter.
Activity 6: Identify common alkalis
LB page 102
Answers
1.
2.
3.
a) An alkali is the opposite of an acid. It is a base that can dissolve in water.
b) Alkalis taste bitter, feel slippery and many are dangerous (corrosive and caustic).
Learners must read the label or list of ingredients on each of five products that contain alkalis.
Learners make a poster for one of the products. Ensure that they include the following information:
•
The name of the product that contains the alkali
•
The chemical name of the alkali and its formula
•
Whether the alkali is strong or weak
•
What the product is used for
•
Whether the product comes with a safety warning
Activity 7: Categorise substances
LB page 103
Answers
1. and 2.
48
Acid
Base
Neutral
Vinegar
Washing powder
Water
Lemon juice
Soap
Sugar
Toothpaste
Salt
Term 2
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Extension for this unit
Ask learners to find out the following information:
•
What happens when there is an acid spill on a road or at a chemical laboratory?
•
What must the clean-up team know before clearing the spill?
•
Are there any safety precautions that must be taken by people affected and by the clean-up team?
Unit 3: Acid-base indicators
Teaching guidelines
Explain to the learners that, because some acids and bases are too dangerous to taste or feel, we need
another way to distinguish between them. Explain that litmus is not the only indicator. Use other
indicators such as universal indicator or phenolphthalein, to illustrate the point about dyes changing
colours. However, the learners only need to know about litmus indicator. Note that detergents and soaps
are expected to be basic, but some contain additives such as lemon juice, and therefore may test acidic
instead. Check for this on packaging labels.
Activity 8: Test known acids, bases and neutrals with red and blue litmus paper
LB page 104
Answers
1.
Colour in acid
Colour in base
Colour in neutral
Red litmus paper
Red
Blue
Red
Blue litmus paper
Red
Blue
Blue
Activity 9: Investigate common beverages to determine whether they are acids,
bases or neutrals
LB page 105
Answers
5.
Substance
Taste
Colour in red litmus
Colour in blue litmus Acid, base or neutral
Water
No taste
Red
Blue
Neutral
Tea
Bitter
Red
Red
Acid
Rooibos
Bitter
Blue
Blue
Base
Milk
Slightly sour
Red
Red
Acid
Fruit juice
Sour
Red
Red
Acid
Fizzy drink
Sour
Red
Red
Acid
6.
Yes
Topic 7: Acids, bases and neutrals
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Activity 10: Investigate household substances to test whether they are acids,
bases or neutrals
LB page 106
Answers
1.
2.
4.
a)
b)
Learners make predictions about which substances they think will be acids, bases or neutrals.
A table similar to the one below that shows all the substances tested
Household chemical
Colour in red litmus
Colour in blue litmus
Acid, base or neutral
Vinegar
Red
Red
Acid
Tartaric acid
Red
Red
Acid
Aspirin
Red
Red
Acid
Antacid
Blue
Blue
Base
Shampoo
Blue
Blue
Base
Soap
Blue
Blue
Base
Bicarbonate of soda
Blue
Blue
Base
Salt water
Red
Blue
Neutral
Sugar water
Red
Blue
Neutral
Liquid soap
Blue
Blue
Base
Lemon
Red
Red
Acid
5.
a)
b)
Acids: vinegar, tartaric acid, aspirin, lemon; bases: antacid, shampoo, soap, bicarbonate of soda,
liquid soap; neutrals: salt water, sugar water
Learners state whether their predictions in question 1 were correct and explain what was different if they were not correct.
Activity 11: Identify unknown substances
LB page 107
Answers
1.
2.
3.
4.
5.
6.
50
An indicator is a dye that changes colour in acids and bases.
Diagram A
Blue litmus turns red.
Diagram B
Red litmus turns blue.
If you only test the substance with one type of litmus, for example red, and it stays that colour the
substance could be acidic or neutral. So, you also have to test with blue litmus to eliminate
one option.
Term 2
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TOPIC 7 REVISION
LB page 108
Science language activity
Answers
Acids taste sour and feel rough on the skin. Strong acids can burn your skin. We say acids are corrosive.
Bases taste bitter and feel slippery. A base that can dissolve in water is called an alkali. Neutrals are
neither acids nor bases. An indicator is a dye that changes colour in chemicals. Acids will turn blue litmus
red and bases will turn red litmus blue.
Test yourself
Answers
1.
2.
3.
4.
5.
a) Any acids, such as vinegar and lemon juice
b) Any bases, such as soap and bicarbonate of soda
a) Oranges, lemons
b) Sour
c) Acidic
d) Citric acid
Toothpaste is a base.
a) Red
b) Blue
c) Blue
d) Blue
e) Red
f) Blue
g) Blue
a) Ethanoic acid
b) Vinegar
c) Corrosive
d) The substance can eat through clothing, stonework and metals, and burn the skin.
e) No
(1)
(1)
(2)
(1)
(1)
(1)
(1)
(7)
(1)
(1)
(1)
(1)
(1)
Total: 20
Topic 7: Acids, baese and neutrals
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TOPIC 8: THE PERIODIC TABLE OF ELEMENTS
Topic overview
This topic begins by introducing the concept of elements and that all the elements are arranged in the
Periodic Table. Learners need to know the names and symbols of the first 20 elements. The properties of
the Periodic Table are discussed: what the groups, periods, symbols and atomic numbers mean. Elements
in the Periodic Table are divided into three main categories: metals, non-metals and semimetals. The topic
discusses the properties of each of these. The topic ends with examples of elements used in everyday life.
Common errors learners make
Learners tend to make up their own symbols that start with the first letters of the elements’ names.
Explain where element symbols come from: they are derived from element names in different languages.
This might help them to remember the symbol. Where learners know more than one language, the names
of elements in the different language may help learners remember the correct symbol.
Resources for this topic
•
•
A copy of the Periodic Table, three colours of pencils or crayons (per learner)
Iron filings, aluminium, copper, a magnet, three test tubes, wires, crocodile clips, a cell, a lightbulb
Starting off
Teaching guidelines
Some materials in the photo of the kitchen look shiny, but are not metals. Explain to learners that
materials like plastic can be made to look shiny even if they are not metals.
Activity 1: Identify the properties of elements
LB page 109
Answers
1.
a)
b)
c)
d)
Cooking pot, stove, fridge, drawer handles
Floor, cupboards, walls
Steel, plastic (in the case of the fridge)
Wood
2.
52
Property
Stainless steel
What does it look like?
Shiny, silver colour, solid
Is it hard?
Yes
Is it strong?
Yes
Can it melt easily?
No
Does it get hot easily?
Yes
Term 2
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Unit 1: Arrangement of elements in the Periodic Table
Teaching guidelines
Introduce the Periodic Table. Keep the information simple. Learners need to learn the names and symbols
of the first 20 elements in the Periodic Table, but they do not need to know the atomic numbers of the
elements. Briefly explain what an element is, but learners deal with this again in Grade 8, so there is no
need to go into too much detail.
Activity 2: Investigate the Periodic Table
LB page 111
Answers
1.
a)
b)
c)
d)
Carbon
6
Silicon, germanium, tin, lead
Lithium, beryllium, boron, nitrogen, oxygen, fluorine, neon
2.
Element name
Symbol
Hydrogen
H
Helium
He
Lithium
Li
Beryllium
Be
Boron
B
Carbon
C
Nitrogen
N
Oxygen
O
Fluorine
F
Neon
Ne
Sodium
Na
Magnesium
Mg
Aluminium
Al
Silicon
Si
Phosphorous
P
Sulfur
S
Chlorine
Cl
Argon
Ar
Potassium
K
Calcium
Ca
Topic 8: The Periodic Table of Elements
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Activity 3: Categorise the elements in the Periodic Table
LB page 113
Answers
1.
In this activity, learners use three different coloured pencils or crayons to colour in the three main
categories of the Periodic Table. Make sure that they also provide a key.
Activity 4: Understand the Periodic Table
LB page 113
Answers
1.
2.
3.
4.
5.
Na
Hydrogen
Silicon, germanium
Semimetal: Ge or As; non-metal: Se or Br or K
a) Non-metal
b) Metal
c) Semimetal
d) Non-metal
e) Metal
f) Non-metal
Extension for this unit
Ask learners to find out whether there are other ways in which the elements of the Periodic Table can be
categorised (other than metals, semimetals and non-metals).
Unit 2: Properties of metals, semimetals and non-metals
Teaching guidelines
Learners have to know the properties of metals, non-metals and semimetals. It is easier for them to
remember them if they actually see them. Therefore, it is a good idea to demonstrate the properties of
different substances to learners even if they do not investigate themselves. Demonstrate how easily sulfur
melts in Activity 6. It may be necessary to explain what the melting point and boiling points are, and what
electrical conductivity and conducting heat means.
Activity 5: Investigate the properties of three different metals
LB page 114
Answers
1.
54
Test
Iron
Aluminium
Copper
Appearance
Shiny
Shiny
Shiny
State of matter
Solid
Solid
Solid
Magnet
Magnetic
Non-magnetic
Non-magnetic
Heat
Does not melt
Does not melt
Does not melt
Electricity
Conducts
Conducts
Conducts
Term 2
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Bend
Bends
Bends
Bends
Stretch
Stretches
Stretches
Stretches
Activity 6: Identify the properties of two non-metals
LB page 115
Answers
1.
2.
3.
Sulfur is yellow and dull; chlorine is light yellow and dull.
Sulfur is a solid; chlorine is a gas.
Low melting and boiling points, because sulfur melts easily and chlorine is already a gas, and so has a
low boiling point.
Activity 7: Identify some semimetals
LB page 119
Answers
1.
2.
3.
A semimetal is a solid element that has properties of both metals and non-metals.
The semimetals are found in the region between the metals and non-metals.
For example, arsenic: shiny, used in poison, and as semiconductors; antimony: shiny, used in plastics
and chemicals; tellurium: shiny, used to make glass and coloured ceramics
Support for this unit
Learners in Grade 7 may not have worked with electrical wires before. Help them to build a circuit to test
the electrical conductivity of the metals in Activity 5. Demonstrate how to use a Bunsen burner before
they have to heat the metals in Activity 5. Alternatively, in a big class, you may want to demonstrate
heating the metals rather than letting the learners do it. Learners can do Activity 5 in groups of 3 or 4.
Extension for this unit
Ask learners to choose 5–10 elements in the Periodic Table and find out who discovered them, and how
they were discovered.
Topic 8: The Periodic Table of Elements
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TOPIC 8 REVISION
LB page 122
Science language activity
Answers
1.
2.
3.
4.
5.
6.
7.
8.
Groups
Periods
Semimetals
Malleable
Metals
Non-metals
Semimetals
Non-metals
Test yourself
Answers
1.
Property
Metals
Non-metals
Semimetals
Appearance
Shiny
Dull
Shiny or dull
State of matter
Solids, except mercury
Solids, liquids and gases
Solids
Conduction of electricity
Good
Poor
Some can conduct
Malleable and ductile?
Yes
No
No
Boiling point
High
Low
High or low
(15)
2.
a)
b)
c)
d)
e)
Lithium
Metal
Sodium, potassium, rubidium, caesium, francium
Carbon, nitrogen, oxygen, fluorine, neon
Boron
(1)
(1)
(1)
(1)
(1)
Total: 20
56
Term 2
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TERM 2 PRACTICE TEST MEMORANDUM
LB page 123
1.
a)
b)
c)
d)
e)
Semimetals
Chromatography
Bases
Mercury
Neutral
(1)
(1)
(1)
(1)
(1)
2.
a)
b)
c)
d)
The temperature at which the liquid starts boiling
Liquid state to gas state.
Distillation
Evaporation and condensation
(1)
(1)
(1)
(2)
3.
a)
b)
c)
(1)
(1)
d)
Sodium
Metal
Any two of the following: shiny, malleable and ductile, conductors of electricity and heat,
high boiling and melting points, solid
H
(2)
(1)
a)
b)
c)
Solid and shiny
It is a good conductor of electricity.
They can be bent and stretched without breaking.
(2)
(1)
(1)
4.
5.
Substance
Acid, base or neutral
Colour in blue litmus
Colour in red litmus
Oven cleaner
Base
Blue
Blue
Sugar water
Neutral
Blue
Red
Soap
Base
Blue
Blue
Vinegar
Acid
Red
Red
(6)
6.
Step 1: Use hand-sorting to pick out the smarties.
Step 2: Filter the mixture to remove the sand and iron filings.
Step 3: Use a magnet to separate the iron filings from the sand.
Step 4: Use distillation to separate pure water from salt water.
(If learners give evaporation for the final step, award 4 marks because the water is then lost.)
(5)
Total: 30
Term 2 Practice test memorandum
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TERM 3
Within Term 3, your Grade 7 learners will cover the following sections of content:
Strand
Topics and time allocation
Unit
LB page
Energy and
change
9 Sources of energy
(3,5 hours)
Unit 1: Non-renewable sources of energy
126
Unit 2: Renewable energy sources
128
10 Potential and kinetic energy
(7 hours)
Unit 1:Potential energy
132
Unit 2: Kinetic energy
136
Unit 3: Potential and kinetic energy in
systems
138
Unit 4: The law of conservation of energy
142
Unit 1: Heating as a transfer of energy
148
Unit 2: Conduction
150
Unit 3: Convection
156
Unit 4: Radiation
158
12 Insulation, energy saving
and energy transfer to the
surroundings
(10,5 hours)
Unit 1: Using insulating materials
164
Unit 2: Useful and ‘wasted’ energy
176
13 The national electricity
supply system
(3,5 hours)
Unit 1: Energy transfers in the national grid
182
Unit 2: Conserving electricity in the home
186
11 Heat transfer
(7 hours)
TERM 3 ASSESSMENT
The following Formal Assessment Tasks will need to be completed in Term 3. You may use the examples
in this book for your learners or you may want to develop your own.
58
Formal assessment
Mark allocation
Learner’s book
page
Teacher’s guide
page
Project: Design an energy-efficient home
25
174
85
Term 3 Practice test
30
191
95
Term 3
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TOPIC 9: SOURCES OF ENERGY
Topic overview
This topic explores different sources of energy, specifically non-renewable and renewable sources of
energy.
Common errors learners make
Energy is not always well understood. Learners often assume that energy is some kind of substance, and
that you can fill a container with energy. This is not so. Try to use the correct scientific language when you
talk about energy. Energy is the ability to do work. In normal language, this means to move, to do things,
to heat things up and to grow. All of these activities require energy.
Resources for this topic
•
•
Textbooks and reference materials
Pictures and reading texts, such as newspaper articles and magazines about non-renewable and
renewable sources of energy.
Starting off
Activity 1: Examine the uses of energy in a photograph
LB page 125
Answers
1.
2.
3.
Cars and trucks moving, lights shining, people walking and plants growing are some options. The list
should also mention people (for example, people’s bodies growing).
Cars and trucks
Plants use energy from the Sun. Humans eat plants and animals.
Unit 1: Non-renewable sources of energy
Teaching guidelines
This topic has general knowledge interest, but also allows for discussions about ‘clean’ energy, global
warming and other areas of environmental science. Ask the class to share what they know about global
warming or environmental issues based on what they have heard at home, in the media or from friends.
There may be aspects that are not clearly understood, and can therefore be clarified as an additional
enrichment exercise.
Activity 2: List non-renewable energy sources
LB page 127
Answers
1.
2.
3.
Non-renewable energy sources include: petrol, diesel, gas, nuclear fuel/uranium, oil and coal.
They are regarded as non-renewable, because when they are used they cannot be replaced, and
eventually they will all be used up.
Non-renewable resources often cause pollution when they are used. They are also running out, which
is a big problem.
Extension for this unit
Let the learners order the non-renewable energy sources that they learnt about in this unit, from most
to least environmentally damaging. There are no clear-cut answers to this exercise, but it will allow
the learners to compare advantages and disadvantages of the energy sources. They should be able to
communicate their reasons for each decision made in this exercise.
Topic 9: Sources of energy
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Unit 2: Renewable energy sources
Teaching guidelines
This is a very interesting topic that has both scientific interest as well as general knowledge interest. When
you discuss the different sorts of energy, give the learners interesting examples and stories, and bring
pictures to enrich your teaching.
Activity 3: List renewable energy sources
LB page 129
Answers
1.
2.
3.
Renewable energy sources include: falling water, wind, tidal power, wave power, solar energy and
biofuels.
They are renewable because we can use them, but we cannot use them up. (They can be restored.)
Firewood is renewable, but if too many people in an area all use the same forest for their firewood,
then the wood will be used up in that area faster than new trees can grow. So, in this way, we can say
it is not always renewable.
Support for this unit
Bring interesting resources, such as pictures, news articles and other texts to enrich your classes. There are
lots of fascinating topics you can add to this section.
Support for learners with barriers to learning
If learners have trouble seeing or reading, or are better able to learn or understand concepts through
investigation, try to bring in examples of the raw materials of the energy sources, such as a piece of coal
or a plant (to explain how plants can be used as fuel (firewood) or about the energy from the Sun and how
plants use it).
TOPIC 9 REVISION
LB page 130
Science language activity
Answers
1.
60
We have two main types of energy: renewable and non-renewable. Energy sources like coal, gas and
oil are called non-renewable energy sources because they will eventually all be used up. These energy
sources can create environmental problems. Energy is also expensive, so we need to use it wisely.
Renewable energy sources like wind energy and energy from falling water will not be used up.
Term 3
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Test yourself
Answers
1.
2.
3.
4.
5.
6.
Energy is the ability to do work.
(2)
Renewable means that it can be replenished or restored.
(2)
Non-renewable: coal, oil and gas; Renewable: wind, water and solar
(6)
We should be using more renewable energy in South Africa because we receive a lot of sunlight and
the wind blows often in many places. Non-renewable energy sources are running out, which is a big
problem for South Africa. Most of the non-renewable sources also produce environmental problems.
They are expensive, whereas renewable energies are a free energy source.
(5)
a) Hydropower is renewable.
b) Solar energy is renewable.
c) Nuclear energy is non-renewable.
d) Fossil fuels/diesel is non-renewable.
(4)
Solar energy is most suitable because we have so much sunshine in parts of our country. Wind is
also suitable, because the wind blows quite often in many places around the country. Water energy
is the least suitable, because we don’t have any major rivers and our waves are too strong for wave
power. Also, the difference between the sea level during high tide and low tide is too little to use for
tidal power.
(6)
Total: 25
Topic 9: Sources of energy
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TOPIC 10: POTENTIAL AND KINETIC ENERGY
Topic overview
This topic describes the difference between kinetic and potential energy. It discusses the three different
kinds of potential energy, namely chemical, elastic and mechanical potential energy. It also covers kinetic
and potential energy transfer in systems. Finally, it explains the law of conservation of energy.
Common errors learners make
Learners make the mistake of thinking energy can be created and destroyed. It is important that energy is
seen as an abstract concept and not as an object. More examples should be given to the learners for them
to see that energy is always present, but in different forms.
Resources for this topic
•
•
•
•
•
•
•
•
•
•
Various examples of food packaging with labels showing energy content
Cells (batteries) per group
1 pair of scissors and paper per group, paper pellet or plastic bottle top, hot and cold water, safety
glasses, cooldrink can, elastic band, a weight, food colouring,
1 ruler per group
1 candle or Bunsen burner and 1 tin can per group
Conducting wire
1 motor per group
2 torch bulbs per group
1 buzzer per group
2 beakers per group
Suggestions for alternative resources
If you do not have laboratory beakers, you can use any clear glass container.
Starting off
Teaching guidelines
Allow the learners to work in small, cooperative groups to respond to the questions. In a big class, you
can split the questions amongst the groups and later discuss the responses as a whole class.
Activity 1: Identify energy systems and different forms of energy
LB page 131
Answers
1.
2.
3.
4.
5.
6.
62
Energy is the ability to do work.
An energy system is a group of parts that work together to transfer energy.
When the athlete runs, movement (kinetic) energy is present, his body becomes warm (heat energy),
and there is also sound energy as a result of his footsteps.
The running athlete has kinetic energy. A body has potential energy when it is at rest.
The energy drink has stored energy in the form of chemical potential energy.
The chemical potential energy in the energy drink is absorbed by the body and is transferred to
kinetic energy as the body of the athlete moves.
Term 3
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Unit 1: Potential energy
Teaching guidelines
Ask learners to bring empty packets of different foodstuffs, such as chocolate bars, cereal boxes and juice
bottles. Divide the material into groups so that each group has a variety of examples. Show the learners
where to find the food labels on the packages. If possible, bring a small chocolate bar for each group to
read the amount of energy contained in it, and then share the bar between the group members.
Activity 2: Identify different types of potential energy
LB page 133
Answers
1.
a)
b)
c)
d)
e)
f)
A compressed spring: elastic potential energy
A boy playing with a catty: elastic potential energy
A candle: chemical potential energy
A car battery: chemical potential energy
Children playing on a trampoline: elastic potential energy
Children playing on a see-saw: gravitational potential energy
Activity 3: Recognise the amount of energy contained in food substances
LB page 134
Answers
1. Learners must read the food labels and identify the amount of energy in 100 g of each of the foods.
Food
Amount of energy (kJ per 100 g)
a)
Chocolate bar
2 203
b)
Cereal
1 300
c)
Roasted peanuts
2 520
d)
Sugar
1 698
Activity 4: Recognise the usefulness of potential energy in our daily lives
LB page 135
Answers
1.
2.
3.
4.
5.
The higher above the ground an object is, the more potential energy it has.
Gravitational potential energy
Water requires a force to push it upstream, therefore a water pump is required to pump the water
upstream.
The water has potential energy by virtue of its height from the bottom of the valley on which it falls.
Possible answers:
•
A car that needs to be pushed before it is started is parked on a slope, so that it possesses
potential energy to move down the slope on its own when the brake is released.
•
A water tank is erected on a stand above the ground so that water can easily flow when the tap is
opened.
•
The roof of a house is built such that, when it rains, water falling on the roof can easily flow
down to the ground.
•
A playground slide works because a child has potential energy when he or she is at the top of the
slide. This gets transferred to kinetic energy as the child slides down.
Topic 10: Potential and kinetic energy
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Support for this unit
Where there is a sense that learners do not understand what potential energy is, or cannot distinguish
between the different forms of potential energy, you may have to perform more demonstrations until
learners understand the concept. Potential energy is a more abstract concept for learners to grasp
(compared to kinetic energy).
Unit 2: Kinetic energy
Teaching guidelines
•
•
•
•
Revisit the concept of simple electric circuits, as learnt in Grade 6.
Link the concept of kinetic to potential energy.
Use many examples to illustrate the concept.
Let learners come up with their own examples.
Activity 5: Identify kinetic energy
LB page 136
Answers
1.
2.
3.
The underlined objects have kinetic energy:
•
Children playing on a roller coaster
•
A child sliding on a slide
•
A moving bowling ball
•
A girl playing with a hula hoop.
Any correct examples will be accepted. Examples include: a man walking; a moving toy; a spinning
wheel; water flowing in a river
Children playing on a roller coaster: When the car reaches the highest point of the track, its potential
energy is at a maximum. This potential energy is converted to kinetic energy as the car moves down
from the highest point.
A child sliding on a slide: The potential energy of the child sitting on the highest point of the slide is
the source of the kinetic energy.
A moving bowling ball: The potential energy of the ball before it was bowled was a result of it being
held above the ground. Once the ball starts moving, it has kinetic energy.
A girl playing with a hula hoop: The kinetic energy of the girl is transferred to the hula hoop.
Extension for this unit
You can extend this unit by asking learners to provide more examples in which potential energy is
changed to kinetic energy, and vice versa.
Skills focus: Draw energy flow diagrams
Activity 6: Practise drawing an energy flow diagram
LB page 137
Answers
1.
64
The flow diagram should take the same form as the examples given in the Skills Focus on page 137 of
the Learner’s Book.
Input: Kinetic energy (a person has to wind up the toy first)
Process: The winding-up motion transfers elastic potential energy to the toy, which is then converted
to kinetic energy as the toy moves across the floor.
Output: Kinetic energy
Term 3
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Unit 3: Potential and kinetic energy in systems
Teaching guidelines
•
•
•
•
•
•
Revisit the concept of a system.
Use many examples to explain the different types of energy systems.
Let learners come up with their own examples as well.
Group the learners into small, cooperative learning groups.
Ensure that all required resources are available to all groups.
Make sure that hot water used is not boiling water, so that learners are not accidentally injured.
The water should be around 50 °C.
Activity 7: Investigate energy transfer in a mechanical system
LB page 139
Answers
Use the following checklist to assess learners.
The learner can:
Yes/No
Remarks
Place a pellet on top of the desk
Bend the ruler at different strengths
Release the ruler to hit the pellet
Explain what happens
Draw the associated energy diagram
Activity 8: Compare kinetic energy at different temperatures
LB page 139
Answers
Use the following checklist to assess learners.
The learner can:
Yes/No
Remarks
Pour water into beakers
Add two drops of food colouring to the water
Make observations
Compare the movement of particles
Draw conclusions from the investigation
Topic 10: Potential and kinetic energy
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Activity 9: Investigate energy transfer in a thermal system
LB page 140
Answers
Use the following checklist to assess learners.
The learner can:
Yes/No
Remarks
Pierce a small hole in the side of a tin can using a nail
Fill the tin can with warm water
Close the tin can tightly
Put the tin can on a stand and light a candle or burner
underneath it
Describe what is observed
Explain where the energy comes from
Explain where the energy goes
Identify the type of energy transfer that is taking place
Draw the energy flow diagram for the system
Activity 10: Investigate energy transfer in an electrical system
LB page 140
Answers
Use the following checklist to assess learners.
The learner can:
Yes/No
Remarks
Connect conducting wires to the bulb and describe what is
observed
Connect the conducting wires to each other after connecting
them to the bulb and describe what is observed
Explain where the energy came from
Draw an energy flow diagram for the system
Activity 11: Investigate energy transfer in biological systems
LB page 141
Answers
1.
2.
a)
b)
c)
a)
b)
c)
66
Chemical potential energy is stored in the grass.
It is transferred to the horse. Some of it will be stored as chemical potential energy in the muscle
cells, where it will be converted to kinetic energy when the horse moves.
horse
Grass
Chemical energy potential is stored in the drink.
It is transferred to the body of the athlete. Some of it will be stored as chemical potential energy
in the muscle cells.
athlete
Energy drink
Term 3
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Activity 12: Identify potential and kinetic energy in systems
LB page 141
Answers
Example of an energy system
Indicate whether it is a
mechanical, biological,
thermal or electrical system
1. A cat drinking milk
Biological system
Chemical energy to movement
energy
2. A pair of scissors cutting a
piece of paper
Mechanical system
Movement energy to movement
and sound energy
3. An electric fan
Electrical system
Electrical energy to movement
energy
4. A hot stone put into some cold
water
Thermal system
Heat energy to sound and heat
energy
5. A windmill
Mechanical system
Wind energy to movement energy
Identify the energy transferred
in the system
Extension for this unit
You can extend this unit by asking learners to provide more examples to show the different types of
energy systems.
Unit 4: The law of conservation of energy
Teaching guidelines
•
•
•
•
Link this unit with Units 1, 2 and 3.
Prepare further examples to illustrate the concepts.
Encourage learners to read the case study individually and as a group.
Explain any difficult words to your class.
Topic 10: Potential and kinetic energy
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Activity 13: Investigate energy transfer in a system
LB page 143
Answers
Use the following checklist to assess learners.
The learner can:
Yes/No
Remarks
Punch two holes in each side of the tin can
Fit a rubber band between the ends
Hang a weight on the rubber band
Give the tin can a slight push
Describe their observations
Identify the type of energy stored in a rubber band
Explain the energy transfer occurring in the system
Activity 14: Investigate energy transfer from one system to another
LB page 145
Answers
1.
2.
3.
4.
5.
Examples may include: When cooking porridge on an electric stove, energy is transferred from the
electrical system to the thermal system in the pot; when riding a bicycle, energy from a biological
system is transferred to the mechanical system of the bicycle.
You need a water trough or wide basin, a toy boat and water.
Pour water in to the basin and the place the doll in the middle when the water in still. Make some
waves from one end of the basin and observe what happens to the boat as the waves reach it. Make
more waves so that they can move the toy boat to the other side of the basin.
(This is only possible if the apparatus is available.)
Energy from a biological system (which causes the waves) is transferred to a mechanical system.
The water transfers its energy to the toy boat to make it move in a particular direction.
Extension for this unit
Allow learners to play a game of marbles, where a marble is made to hit another marble, and let them
explain the energy transfer that is involved.
68
Term 3
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TOPIC 10 REVISION
LB page 146
Science language activity
Answers
1.
When a weightlifter lifts a weight, the chemical potential energy stored in his body makes it possible
for him to lift the weight. When the weight is lifted above his head, it has gravitational potential
energy. If he slips and lets it go of the weight, it will gain kinetic energy, which makes it land on the
ground again. If the weight plates are covered in rubber, the weights will not crush the floor, but will
bounce up and down because of the elastic energy of the rubber. The weightlifter activity illustrates
the law of conservation of energy, which states that energy cannot be created or destroyed but can be
transformed from one form to another. The unit for measuring the energy of the weight is the joule.
Test yourself
Answers
1.
2.
Kinetic energy is the energy a moving object has, and potential energy is the energy an object has
when it is at rest.
(2)
If you put fuel in a car and the car moves until the fuel is finished, the energy in the fuel has not been
destroyed, but has been changed into sound energy, heat energy and movement energy. If there was
a way of collecting the energy from the sound, movement and heat, it will still be same amount of
energy that was present in the fuel at the beginning.
(3)
3.
Energy
system
What is the form
What is the
of potential
energy input?
energy?
Where is the
energy going?
What is the form of
kinetic energy?
Burning coal
Chemical
Coal
Heat
Movement of particles
in the coal and the
surrounding air
An electric fan
Chemical
Electricity
Motor
Movement of fan blades
A person
blowing a
vuvuzela
Chemical
Person
Vuvuzela
Sound energy
(12)
4.
Energy system
Example of this
energy system
Type of energy that is used in this energy system
Mechanical
Riding a bicycle
Kinetic energy
Electrical
Radio
Sound energy
Biological
Eating a sandwich
Chemical potential energy
Thermal
Hot bath
Heat energy
(8)
Total: 25
Topic 10: Potential energy and kinetic energy
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TOPIC 11: HEAT TRANSFER
Topic overview
This topic explains that heating is the transfer of energy from warmer objects or places to cooler objects
or places. It also describes the three ways in which heat energy can be transferred, namely conduction,
convection and radiation. Conduction is described as the transfer of heat through physical contact,
convection is the transfer of heat in liquids and gases, and radiation is the transfer of heat without the use
of any medium.
Common errors learners make
Learners tend to think that heat is the same as temperature. Heat and temperature are two different
things. This point must be made as conduction is defined. An object may have a high temperature but
transfer little heat.
Resources for this topic
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Video clips from the Internet to show conduction, convection and radiation
Spirit or Bunsen burner, one per group
Steel, brass, aluminium and iron rods, one set per group
Styrofoam cup, one per group
Wood cup, one per group
Plastic cup, one per group
Aliminium cup
Glass cup, warm water, stopwatch or cellphone with stopwatch function, tripod stand, sawdust,
beaker or glass jar (250 ml)
Wax or Vaseline
Drawing pins
Heat conducting tins (if available)
Wristwatch with a second hand, or a stopwatch, one per group
Clear glass or plastic bottles with plastic lids (500 ml)
Hot water, newspaper
Food colouring or crystal of potassium permanganate (beetroot juice will also do)
Glass/transparent plastic container
Candles
Shiny silver surfaces (wrapped by aluminium foil or silver cloth)
Matt black surfaces (painted matt black) (black cloth)
Thermometers
Cardboard or paper and glue
Suggestions for alternative resources
•
•
You can use beetroot juice as a food colouring.
You can use 500 ml plastic bottles and use silver and black paint to paint them
Starting off
Activity 1: Find out what you know about energy and energy transfer
LB page 147
Answers
1.
70
Energy is the ability to do work and energy transfer is the movement of energy from one point to
another.
Term 3
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2.
3.
4.
5.
6.
The four systems through which energy can be transferred that were learnt about in Topic 10 are:
•
mechanical systems
•
electrical systems
•
thermal systems
•
biological systems.
The Sun fits under thermal systems.
Thermal energy is energy produced by heat. An example is when your body is warmed by warm water
in a bath.
B
It is cold in winter, so when you stand in direct sunlight you can be warmed by the heat from the Sun.
Unit 1: Heating as a transfer of energy
Teaching guidelines
Revise Topic 10 in detail in terms of energy transfer, but focus on examples of thermal energy. More
examples will help learners to conceptualise heat as energy transfer. Let the learners come up with their
own examples. Let them see if they can identify the type of medium required for heat transfer.
Activity 2: Describe examples in which heat energy is transferred
LB page 149
Answers
1.
Figure 5: When sharpening a pencil, the friction between the pencil sharpener and the pencil
produces heat, which is transferred to both the pencil and the sharpener.
Figure 6: A hairdryer produces warm air that is transferred to dry your wet hair.
Figure 7: An iron has a hot base that transfers heat to iron the clothes.
Figure 8: When your lips touch a cup of hot chocolate, the heat from the hot cup is transferred to
warm your lips.
Figure 9: Burning wood in a fireplace produces heat, which is transferred to warm the entire room.
2.
Medium required
Example
Liquids
Drinking hot chocolate
Gases
Burning wood
Solids
Using an iron
No medium (vacuum)
None. (There can be no heat
transfer in a vacuum.)
Support for this unit
Give learners more real-life examples to explain heat transfer.
Topic 11: Heat transfer
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Unit 2: Conduction
Teaching guidelines
•
•
•
Allow learners to work in small, cooperative learning groups.
Provide a safety alert for working with warm or hot water.
Check the temperature of the water with a thermometer to ensure that it is below 60 °C before giving
it to learners.
Activity 3: Explain heat energy transfer by conduction
LB page 151
Answers
1.
2.
3.
4.
Heat transfer in each picture:
Figure 14: Heat is transferred from the iron to the clothing.
Figure 15: Heat is transferred from the mug of tea to the hands holding the mug.
Figure 16: Heat is transferred from the hot tarmac to the feet of the child.
The learners’ diagrams need not show much detail, but what is important in each, is that the arrows
are correct:
Figure 14: Arrows from the iron to the clothing
Figure 15: Arrows from the cup to the hands
Figure 16: Arrows from the tar road to the feet
Learner’s answers will vary, but the following can be referred to if the learners struggle to find their
own examples.
•
Burning a candle transfers heat from the flame to the room.
•
Computer heat sinks draw heat away from heat-sensitive computer components.
•
Bathwater transfers heat from the water to the person bathing.
Learner’s answers will vary, but the following can be referred to if the learners struggle to find their
own examples:
•
Mining: Melting gold to make gold bars
•
Manufacturing industry: Glass production
•
Electricity generation: Cooling towers
Activity 4: Investigate heat energy transfer in various substances
LB page 152
Answers
Use the following checklist to assess learners.
Learners can:
Yes/No
Remarks
Touch the cups to check how warm they are before
the investigation
Half-fill each cup with warm water
Touch the cups to check how warm they are after
the investigation
Determine which cup feels the warmest
Order the cups from warmest to coolest
Answer the question: Which material is the best
conductor of heat?
Answer the question: Which material would be a
good insulator?
72
Term 3
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Extension for this unit
Learners can be given thermometers and told to redo Activity 4, to see which cup was still warm after
10 minutes.
Skills focus: Identify variables that affect results
Activity 5: Practise identifying variables that affect results
LB page 154
Answers
1.
•
•
•
2.
•
•
•
The independent variables are the marshmallow and the peanut.
The dependent variable is the amount of energy produced (as indicated by the temperature of
the water).
The control variables are the amount of water in the test tubes, the time taken and the type of
test tube used.
The independent variables are the silver mat and the black mat.
The dependent variables are the hotness or coldness of the mats.
The control variables are the time taken, the material of the mats and the exposure to the Sun.
Topic 11: Heat transfer
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FORMAL ASSESSMENT
Practical task: Investigate heat conduction of various metals
LB page 155
Teaching guidelines
•
•
•
•
•
Cut enough 20 cm sections of the metal rods so that there are enough for each group of learners.
Organise one-plate stoves for each group for them to prepare the hot water.
Demonstrate to the learners how the investigation is to be conducted.
If the candle wax is not working well, use some Vaseline and drawing pins.
Prepare a step-by-step worksheet to give to the learners to complete and submit at the end of the
activity for assessment.
Assessment tool
In a large class, the rubric on the next page can be used for assessment.
Support for learners with barriers to learning
•
•
74
Arrange an appropriate sitting arrangement for learners with disabilities, so that they are not exposed
to danger.
Repeat the instruction in small groups where you have learners who have hearing or sight challenges.
Term 3
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Assessment criteria
Mark allocation
Learners can:
0
1
2
1. Use a ruler to mark
each rod at 12 cm.
None of the rods
are accurately
measured.
At least two of the
rods are accurately
measured.
Accurately
measured 12 cm
on each rod
2. Place candle wax at
the 12 cm point on all
four rods.
None of the rods
have candle wax
placed at the
correct point.
At least two of the
rods have candle wax
placed at the correct
point.
All four rods
have candle wax
placed at the
correct point.
3. Write a testable
question for the
investigation.
No question written
Which metal conducts
heat better?
4. Write the aim of the
investigation.
No aim provided
The aim is to
determine which metal
conducts heat better.
5. Make a prediction of
the outcome of the
investigation.
No prediction
Prediction made
Accurate
predictions made
6. Use a stopwatch to
record the time.
Cannot use a
stopwatch
Can use a stopwatch
with fair accuracy
Stop watch
correctly used
7. Mark the time at which
the wax begins to melt
for each of the metal
rods, and record results
on the table provided.
Table not
completed
At least two metals
completed on the table
Three metals
recorded
All metals
completed
on the table
8. Draw a bar graph to
show the results.
Cannot draw a bar
graph
Bar graph drawn, but
with no labels
Bar graph drawn
with labels, but
not accurate
Accurately
drawn bar
graph with
labels
9. Write a conclusion.
No conclusion
Correct conclusion
written, identifying
which metal is a good
conductor
10. a) Identify
independent
variables that could
affect the findings.
Not done
Correctly identified the
different metals
10. b) Identify dependent
variables that could
affect the findings.
Not done
Identified time taken to
melt candle wax
10. c) Identify control
variables that could
affect the findings.
Not done
Amount of heat
identified
3
Total: 20
Topic 11: Heat transfer
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Unit 3: Convection
Teaching guidelines
Arrange sufficient resources for each of your groups. Make sure your groups have responsible learners
as group leaders, for safety purposes, as they will be working with warm or hot water. Always check
the temperature of the water given to learners and make sure that it is below 60 °C (to avoid potential
accidents).
Activity 6: Investigate convection
LB page 156
Answers
Use the following checklist to assess learners.
Learners can:
Yes/No
Remarks
Yes/No
Remarks
Put water and a small amount of sawdust in the beaker
Stir the water to spread the sawdust
Place a candle or Bunsen burner underneath one side of
the beaker and light it, without the water boiling
Observe carefully what happens to the sawdust
Draw a labelled diagram to show the movement of the
sawdust
Use their diagram to explain how convection occurs
Activity 7: Demonstrate convection
LB page 157
Answers
Use the following checklist to assess learners.
Learners can:
Fill up one bottle with hot water
Fill up the other bottle with cold tap water
Cover the mouth of the bottle with cold water with a thin
sheet of newspaper and invert it into the mouth of the bottle
with hot water, and hold the bottles tightly
Predict what will happen as the cold water meets the warm
water
Observe what happens as the water gets through the thin
layer of newspaper
Write a conclusion based on their observations
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Activity 8: Explain how convection occurs
LB page 157
Answers
1.
2.
3.
Hot air rises, therefore the heater is best positioned on the floor so that as the warm air rises, the
cooler air sinks down to be warmed by the heater until the whole room is full of warm air.
In summer, the air conditioner is best positioned next to the ceiling, since the cool air generated by
the air conditioner sinks and the warm air rises (to be cooled by the air conditioner) until the room is
eventually filled with cool air.
Water expands as it gets warmer and it rises. The movement of water creates currents that circulate
the water around the fish tank. In this way, all the water in the fish tank (not just the surface water) is
kept warm.
The fireplace also uses the concept of convection, in that the warm or hot air around the fire rises
through the chimney and carries smoke with it. Hence, we do not have smoke in the room. It is only
when the wood is not burning properly that you have smoke in the room. Another example is a hot
air balloon: the hot air inside the balloon causes it to rise because hot air rises.
Extension for this unit
Ask learners to go home and cook macaroni under the supervision of their parents. Ask them to watch
how the macaroni behaves in the pot as the water warms up.
Unit 4: Radiation
Teaching guidelines
•
•
•
Use a dictionary to explain the terms in this unit (radiation, electromagnetic waves, vacuum, solar
energy) to help learners obtain a working definition of these words.
Work in small, cooperative learning groups.
Make sure there are enough resources for the groups.
Activity 9: Explain how radiation occurs
LB page 159
Answers
1.
2.
3.
4.
The fire does warm the room through convection, but the room is mainly warmed by radiation, since
the red-hot coal and flame radiates heat energy (which you can feel when you stand next to the fire).
It means that fire does not need air or a liquid to warm up a space. Special waves, called
electromagnetic waves, carry the heat around the room.
Radiation is used to heat food in a microwave oven.
People and animals need the energy from the Sun for warmth. The Sun radiates energy to all
objects. It does not require a medium such as air.
Activity 10: Answer questions about radiation
LB page 160
Answers
1.
2.
3.
The Sun’s radiation
They can place their ingredients next to a burning fire.
Brewing traditional beer; making traditional clothing from animal skin; making of shoes from
animal skin; making mats from weeds; drying meat and other food items such as beans and maize
Topic 11: Heat transfer
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Activity 11: Investigate radiation
LB page 161
Answers
Use the following checklist to assess learners.
Learners can:
Yes/No
Remarks
Fill the two bottles with tap water
Create holes on the lids to insert the thermometers
Close the bottles and take the readings on the
thermometers; record the readings in the given table
Cover the bottles with the cloth: one bottle with the black
cloth and the other bottle with the silver cloth, while making
sure that they can still read the thermometers
Put both wrapped bottles in direct sunlight
Record the reading of the thermometers every 30 minutes.
Identify which bottle recorded the highest temperature after
two hours
Draw a conclusion from their observations
Draw a line graph to present their findings
Explain why it is not advisable to wear a black dress or
jersey on a hot day
Explain why they would not buy a black car, if they lived in a
hot area
Support for this unit
Repeat the investigation with some learners, if necessary.
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TOPIC 11 REVISION
LB page 162
Science language activity
Answers
1.
2.
3.
4.
5.
6.
Heat transfer through physical contact of objects
Heat transfer without a medium such as air or liquid
Heat transfer though liquids and gases
A material that does not transfer heat
The circular movement of fluids caused by convection
A material that transfers heat well
Test yourself
Answers
1.
2.
3.
4.
5.
6.
This is because black material absorbs heat from the Sun more than white material does.
(2)
Black materials absorb more heat energy than silver materials do. Shiny, sliver materials reflect
light and heat.
(2)
Hot air rises, so the air around the heater gets warm and rises to the ceiling. Cold air sinks down to
be heated by the heater, and rises up until the room is filled with warm air. This kind of heat energy
transfer is called convection.
(3)
The base of cooking pots conduct heat from the stove and transfer it to all parts of the pot. If the
handle was not made of a material that conducts heat poorly, such as wood or plastic, it would be
so hot that you would not be able to touch it.
(2)
a) A black car would absorb heat and would be far hotter to travel in than a lighter-coloured car. (2)
b) You will need: a black mat, a white mat and a thermometer
Method:
•
Fold the mats in the same way.
•
Put a thermometer in the same position on each mat. Do this inside the same room, so that the
thermometers have the same initial temperature.
•
Place the mats in direct sunlight (outside) at the same time and leave them for at least one hour.
•
Check the temperature of the mats.
•
You will find that the reading on the thermometer on the black mat will be higher than the
reading on the thermometer on the white mat.
(3)
•
The hotplate transfers heat energy to the pot by conduction.
•
The pot transfers heat energy to the water by conduction.
•
The water warms up to boiling point by convection.
•
The hotplate and hot pot transfer heat to the surroundings by radiation. (Any three)
(6)
Total: 20
Topic 11: Heat transfer
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TOPIC 12: INSULATION, ENERGY SAVING AND ENERGY
TRANSFER TO THE SURROUNDINGS
Topic overview
Topic 11 covered the three methods of heat transfer, namely convection, conduction and radiation. This
topic incorporates all three methods, but specifically focuses on the aspect of conduction that prevents
heat loss – insulation. The opening page starts with heat loss from a teenager’s body. Unit 1 addresses the
heat loss problem and the importance of preventing heat loss. By the end of this unit, learners will have
sufficient knowledge to design a home that prevents heat loss. The final unit discusses wasted energy in
energy transfers, and how to maximise the transfer into workable energy.
Common errors learners make
Learners may confuse the conservation of energy with energy efficiency. Energy efficiency refers to energy
input being converted to useful energy with minimal wasted energy. Conservation of energy refers to the
fact that energy is never created or destroyed, but is transferred from one form to another. Conservation
of energy can also refer to people using methods to save energy in homes and other areas. This saves
electricity, which is important in the preservation of fossil fuels and cutting costs.
Resources for this topic
Appeal to the learners, their parents, the rest of the school and the teachers to bring in materials for you
to use at least one month before you start this topic.
•
Pictures/diagrams of solar water heaters
•
Video clips from the Internet
•
Cooking pot (or container), cardboard box to make a ‘hot box’, insulation materials such as paper,
fabric, cushions and blankets
•
Pictures or examples of tools/appliances such as an electric drill, electric iron, kettle, food mixer
•
Thermometers (maximum of 4 per group)
•
A container made out of a heat conductor such as steel (one per group)
•
A container made out of a heat insulator such as Styrofoam, big enough so that a conducting
container can fit into it (one per group)
•
Stopwatch or cellphone with a stopwatch function (one per group)
•
Hot, just-boiled water; cold water
•
1 ℓ boiling water; metal, glass, plastic and Styrofoam containers (all 250 ml capacity) (Act 4)
•
Insulating materials: metal, glass, Styrofoam, plastic, a piece of newspaper (sufficient insulating
materials per group)
•
Section of black pipe at least 5 m long; hosepipe or jug with water; bucket; plastic bottles or tubing
(Act 3)
•
Sticky tape
•
Materials to build model house (sufficient materials per group)
•
Insulating sheets for the roof of the model house. Each group must choose two e.g. newspaper,
polystyrene, glass, fibreglass or fabric
•
Identical containers to measure the cooling of hot water (two per group)
•
Lamp (one for the class)
•
Extension cord (one for the lamp class)
•
Different types of light bulbs, incandescent and energy saving (as many different types as you can get,
only one of each is required per class)
•
Ruler and or tape measure (one for the class)
•
White towel (one for the class)
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Starting off
Teaching guidelines
There are many examples of thermograms. If you have access to the Internet, go to www.sciencephoto.com
to select some other examples, such as a tree or animals, so that a comparison of the heat produced from
animals with different body temperatures or various objects, can be made. Try to print a few of these in
colour.
Activity 1: Identify areas of heat in the human body
LB page 163
Answers
1.
2.
3.
4.
Heat
a) Nose and hair
b) These are the areas where the most heat loss occurs. The extremities of the body lose the most
heat.
c) Cover your head with a balaclava. This will cover the hair and nose. Wearing a hat will prevent
heat loss from the hair.
a) Heat is lost from the extremities of the body such as the feet and hands. Wearing socks, gloves
and a hat makes a big difference to keeping warm in winter.
b) Your face. Heat is lost from the extremities of the body.
No. Variations occur according to size, mass and metabolism.
Unit 1: Using insulating materials
Teaching guidelines
This topic links closely to Topic 11. Consolidate the three methods of heat transfer. The start of the unit
sets the platform for energy efficiency. Learners need to understand the heat loss problem in Physical
Science. This is when heat naturally flows from a hotter body to a cooler body. From here, lead into a
discussion on the need to keep heat in objects or organisms by referring to examples learners can relate
to, such as wearing jerseys in winter or heating rooms. While the focus of this unit is on keeping heat
in objects, you must mention that insulating materials can also be used to keep people or objects cool.
Illustrate this with everyday examples such as the use of thermos flasks or cooler bags. Try to use as many
everyday examples as possible in this topic. Also focus on insulating materials that are commonly used in
the area of the school and the homes of learners. Discuss insulating materials in relation to:
•
different budgets, such as lining your walls with posters if you are working with a low budget
•
different situations, for example preventing heat loss if suffering from hypothermia
•
availability of materials
•
greening practices, such as whether or not the material is biodegradable.
Activity 2: Measure temperature difference
LB page 164
This can be done as a demonstration if you do not have sufficient apparatus. If the learners are doing
their own thermometer readings, teach them to read a thermometer beforehand. They will need to keep
their eye in line with the exact measurement line to avoid the error of parallax.
The idea for this activity was taken from the following website: http://www.physicsclassroom.com/class/
thermalP/u18l1e.cfm
Although it is complicated, try to read through the information on this website before doing this
experiment.
Topic 12: Insulation, energy saving and energy transfer to the surroundings
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Heat moves from one container to the other, until equilibrium is reached. The temperature is changing
because of the heat transfer from the hot water to the cold water. The hot water is losing thermal energy.
The cold water is gaining thermal energy.
The results must follow this trend:
•
The water in the conducting container loses heat.
•
The water in the Styrofoam container gains heat.
•
The water in both containers end up at approximately the same temperature.
Answers
6.
a)
b)
c)
d)
e)
f)
The temperature decreased.
The temperature increased.
Answers will vary according to the size of the containers and the amount of water used.
Inside to outside
The heat conductor loses heat easily. The heat will move from the hot water to the cold water.
The heat will be kept in the insulator, ensuring the state of equilibrium. If the outer container
was made of a conductor, it would lose heat to the exterior. Equilibrium would not be reached.
The heat would not leave the middle container. The insulating material prevents heat loss. (Apply
this to an everyday situation, such as wearing a jersey prevents heat loss from the body to the
exterior environment.)
Activity 3: Evaluate solar heating system designs
LB page 166
If you have time, you could try to build a solar water system with your class using the method given.
However, the evaluation of the design is the important part of this process, so this should be your focus.
Answers
1.
2.
82
Radiation: The solar collector captures the heat waves. The transparent surface allows for the transmission of the heat waves. The dark, dull interior is designed to absorb radiation.
Conduction: The insulation of the solar collector traps heat energy. The copper tubes are made of
copper that easily conduct the heat once it is captured.
Convection: The element is placed at the bottom of the geyser. Hot water rises.
a) To investigate which arrangement of tubes (solar collector) captured the most heat.
b) The flat design, (d). The pyramid design is also very efficient at trapping rays because the 360°
design traps the Sun’s rays from all sides. See:
http://www.iol.co.za/scitech/science/environment/local-inventors-flip-switch-on-solarelectricity-1.1250704 to read about the Turboheat Solar Spiral, which was invented by a South
African, Alan Walton, in 1996.
c) (a)
d) The bottles are filled with air. Air is an insulator. You can mention that this design would be
more effective than (a), but less effective than (d) due to the quantity of tubing used.
e) As a control for water temperature. In an experiment, a control is used for comparison.
f) The best design to capture the maximum heat in a solar collector.
g) Independent variable: the different designs (a), (b), (c) and (d).
Dependent variable: the water temperature
Controlled variables: the same type of pipe was used, and the water temperature is measured at
the same position.
h) Repeat each design three times and take the average temperature. Use a digital thermometer for
accuracy. Have a longer testing period to compare the absorption in different weather.
Note: improvements are not extensions.
i) Test different colour tubing and different widths of tubing.
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Activity 4: Analyse a thermogram of a home
LB page 167
This activity ties in with the topic opener activity, and sets the scene for the project. Some learners may
find it difficult to interpret the thermogram. Focus on the hottest and coldest areas of the house. Your
emphasis must be related to the importance of the knowledge of heat loss areas of the house in order to
maintain warmth and prevent wastage. Ask the question: How would you identify these areas in your
house without using a thermogram?
Answers
1.
2.
3.
4.
Chimney and rooms (possibly bedrooms), walls, edging of the roof/garden protected by the roof, top
roof, lower roof, area outside the house (possible snow)
Winter. It seems as if there is a fire in the chimney, the rooms are heated and there is snow outside.
Roof. The roof must contain an insulation material that helps retaining the heat energy.
a) Windows
b) Cover the windows with an effective insulator such as thick woollen curtains. This will prevent
excessive heat loss through windows.
Activity 5: Investigate the effectiveness of insulating materials
LB page 168
Try to do group work, but if you do not have sufficient equipment, do a demonstration and record the
answers on the board. The learners can then create their own bar graph and provide answers to the
questions.
Answers
6.
7.
8.
a)
b)
Learners’ answers will vary.
The results should show that the metal in the newspaper lost the most heat, but that the newspaper would have helped. Average the different groups’ results and draw a final conclusion from the
shared data. All of the materials, apart from the metal, are insulators, so the results will show a
range of best to worst insulators.
This is not a fair test for the following reasons:
•
There is no control. The metal should have been tested on its own, or one of the insulators (such
as Styrofoam) could have been wrapped in newspaper to make a comparison.
•
Each container should have been tested three times and the results averaged.
Good insulators (such as Styrofoam) slow heat loss, while poor insulators (such as metal) result in
faster heat loss. The order of materials on learner’s lists may vary slightly, but make sure that they
understand the concepts correctly.
Activity 6: Read and write about a biodegradable insulator
LB page 170
This is one of several organic insulators. Others are made from rice and soya beans. Ask the class what the
benefits of using an organic product are, and what the disadvantages may be.
Answers
1.
‘Sustainable housing’ refers to a home that is self-reliant, in other words, it does not require energy
from sources such as coal; it is energy-efficient and makes use of natural methods to prevent heat loss.
‘Patented’ is a word used to protect the rights of an inventor. A new design could be used by other
people for credit, and more problematically, to make money. Even new ideas created by junior and
senior learners at regional and national science expos require the completion of a patency form, in
case the idea is ‘stolen’ by someone viewing the projects.
Topic 12: Insulation, energy saving and energy transfer to the surroundings
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2.
3.
4.
a) Oyster mushrooms
b) Any three of the following are acceptable: Newspaper, stryrofoam, plastic and fibreglass
A natural product has been used as an insulation material. It is biodegradable and does not harm the
environment or people. In contrast, fibreglass has the potential to cause physical harm to people.
a) It is a biodegradable, natural, fire-resistant, cheap to produce and a better insulator.
b) The material needs to be protected from decomposition, and people may be skeptical about
its use.
Activity 7: Evaluate effective use of insulators in a house
LB page 170
This is a quantitative method to compare insulation. You can look up U-values of other materials for
comparison purposes – if you have access to the Internet, use ‘U-values’ as a search term in a search
engine.
Answers
1.
2.
a)
b)
It traps heat significantly.
There is a difference in U-value of 2,7. Air is a poor conductor of heat, therefore the layer of air
between the two sheets of glass is a good insulator.
c) The floor – use carpeting; the doors – use hinges that allow doors to be opened slowly. Materials
such as wood, tiles and fabrics should have U-values.
The cost of the material, whether it is harmful to humans and the environment, its durability and
availability
Support for this unit
Bring interesting resources, such as pictures, news articles and other texts to enrich your classes. There are
many resources available online (if you have access to the Internet), and websites such as
http://inhabitat.com/ are a good place to start.
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FORMAL ASSESSMENT
Project: Design an energy-efficient home
LB page 174
Part 1: Eco-homes/environmentally friendly homes
1.
2.
a)
A home that:
• has no harmful impact on the environment
• is made with natural materials
• is energy-efficient in the design and use of materials
• uses ‘green’ methods to save energy, such as worm farms and LED lights.
(3)
b) The design of the home and the materials used capture maximum natural energy and prevent the
loss of this energy during cold weather.
(2)
Learners may know other methods that are practiced by their families, friends or communities. They
can share their ideas.
(1)
Part 2: Indigenous and traditional homes
1.
a)
b)
c)
2.
a)
b)
Natural
(1)
Models of the same specifications can be made of the homes. The temperature inside the home
and outside the home can be tested during different types of weather. The difference can be
calculated and compared. If possible, try to interview people living in these homes.
(3)
Availability, costs, knowledge of insulation and sharing of knowledge by people who have homes
made from certain materials. Culture can also be named as a good reason.
(3)
Dome shape (less surface area is exposed to the Sun’s radiation)
(1)
In winter, it will be an advantage because hot air rises.
(1)
Part 3: Interviews
Learners should be encouraged to interview people, even if the results are not as practical or useful as
imagined. The text provided in the Learner’s Book should be considered as a guide to conducting the
interviews, but if interviews are impossible to conduct, then the text should be discussed in class and
learners should contribute their own ideas about natural ways of insulating homes.
Part 4: Make roofing for a model house
Teaching guidelines
Scaffold the project for the learners:
•
Discuss the purpose of the investigation.
•
Discuss how you will do the investigation.
•
Identify the variables.
•
Cut the different roofs in class. Check that the learners are cutting them the same size.
Topic 12: Insulation, energy saving and energy transfer to the surroundings
9780636140905_plt_nat_g07_tg_eng_za.indb 85
(5)
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Part 5: Test different roofs
Teaching guidelines
•
•
If there is not enough equipment for all the groups, then the groups can have turns to test their
materials. Normal work can continue during the testing phase, as it only requires thermometer
readings.
Discuss whether this is a valid test. Ask the question: If there are no thermometers, is it valid to feel
the temperature differences in the containers?
Assessment tool
Mark allocation for the table:
Detailed heading
Headings for far left column
Headings for top row
Values for the start temperature
Values for the temperature after 10 minutes
Temperature differences
(2)
(1)
(1)
(1)
(1)
(4)
Part 6: Evaluation
Answers to the questions:
1. Independent variable – different insulation materials of the roofs
(1)
Dependent variable – temperature loss
(1)
Controlled variables – tested in the same conditions, used the same house, same size roofing, same
size containers, same amount of water
(2)
The answers to questions 2, 3 and 4 are dependent on the learners’ specific experiment.
2. Analyse your results and give a conclusion for your investigation.
3. How effective do you think this method was in testing insulation? Explain your answer.
4. Suggest three ways that you could improve this investigation.
(2)
(1)
(3)
[40 ÷ 2 = 20]
Total: 20
Support for learners with barriers to learning
You can either choose mixed-ability groups or give extra assistance to learners that require extra support.
For example, provide them with the roofing options. You could give them more insulation materials
to test, in order to compensate for doing the work for them (additional materials could be fabric,
polystyrene, wood, cotton wool and cork). These results can be discussed with the class. It is important
not to highlight these learners as ‘special’, so be discreet and not patronising.
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Unit 2: Useful and ‘wasted’ energy
Teaching guidelines
This unit links closely with the other topics covered this term. It is easiest to teach this in an equation
format, as below:
input energy – useful output energy = ‘wasted’ energy
In any situation, the useful energy must be maximised and the wasted energy minimised. The extent to
which this is achieved determines the energy efficiency. For example, a house where a large amount of
input energy is converted to useful energy, with minimum wastage, will be far more energy-efficient than a
house that has a large amount of wasted energy and minimal useful energy.
Activity 8: Calculate the energy efficiency of a power plant
LB page 177
Answers
1.
2.
3.
4.
5.
6.
62%
2
× 100)
5% ( 38
36%
100%
36%
34%
Activity 9: Draw energy flow diagrams
LB page 177
Answers
For each of the examples in the table, the learners must draw energy flow diagrams using different size
arrows to show the energy inputs and outputs.
Activity 10: Evaluate human-powered cars
LB page 178
Answers
1.
2.
3.
Some ideas that could be considered include: No energy source (such as petrol) used; healthy lifestyle
(lots of exercise); not harmful to the environment; small, so it is easy to find parking
Some ideas that could be considered include: No protection from the weather; there is little space to
put parcels or bags; if you are tired or sick, you may not feel up to pedalling; may slow down traffic;
travelling times are greater, so you have to leave much earlier for appointments
Its streamlined shape (reduces air resistance); it is small (and less energy is required to move a small
object); the white colour reflects radiation
Topic 12: Insulation, energy saving and energy transfer to the surroundings
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Activity 11: Investigate thermal energy loss in light bulbs
LB page 179
People may not realise that a by-product of incandescent light bulbs is heat. The new CFLs and LED
lights produce only a fraction of the heat produced by incandescent light bulbs. Thermal energy is the
energy that is ‘lost’ from incandescent light bulbs, and refers to the part of the internal energy of a system,
which is the total present kinetic energy resulting from the random movements of atoms and molecules.
Worksheet: Thermal heat
Name: _______________________________________________ Date: _____________________
Bulb
Temp at 1 min
Temp at 2 min
Temp at 3 min
Temp at 4 min
Temp at 5 min
20 W Bulb
40 W Bulb
60 W Bulb
100 W Bulb
CFL _____W
CFL _____W
ANALYSIS
1.
2.
3.
4.
Which bulb produced the most heat? ____________________________________________
Which bulb produced the least heat? ____________________________________________
Which bulb do you think is better to use? _________________________________________
Draw a graph to represent the data collected.
Chart title: ______________________________________________
Answers
The answers to the questions are dependent on the experimental results.
Support for this unit
The following question set can be given to those learners who struggle with the concepts introduced in
this topic. These question sets offer good revision of the preceding units and topics as a base upon which
to introduce the concepts of energy system and energy flow diagram.
1. Think of a person eating an orange.
a) What is the major energy source in this energy system?
b) What form of energy/energies does the Sun have?
c) How does energy move from the Sun to the oranges?
2. Think of a group of learners playing soccer.
a) Identify the energy transfer that occurs in the children playing soccer.
b) What happens to the energy that the children use while they are playing soccer?
c) The children decide to sit down and eat some oranges. Identify the energy transfer that takes
place.
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Find a newspaper or magazine article (printed or online, if you have access to the Internet) that lists ways
of reducing fuel consumption. Print out the article for those learners who require extension, and:
1. Ask them to draw a table consisting of two columns. In the first, they need to tabulate the recommendations to reduce fuel consumption (from the article) and in the second column of the table, provide
reasons for this recommendation to test their comprehension of the article. If there are no reasons for
the recommendation, the reason is to cut fuel consumption.
2. They can then use the table to design a poster of tips for motorists to cut fuel consumption.
TOPIC 12 REVISION
LB page 180
Science language activity
1.
Learners may be tempted to write definitions. However, they must write sentences showing that they
understand the meaning of the words – even if their contexts are not necessarily those that were
referred to in the Learner’s Book. The words should be used exactly as they are for example, for heat
loss, the sentence ‘heat comes in and is lost through windows’ would not be an acceptable answer. A
few examples of what would be acceptable are given below:
a) Heat loss occurs from pipes and tanks when they are not insulated properly.
b) The majority of solar heat gain is through windows and open doors in houses.
c) Building insulation prevents heat loss from houses.
d) Solar energy is a renewable energy source.
e) Input is required by all members of an organisation to ensure success.
f) The output of the company fell in June due to a flu epidemic.
g) There are many energy systems in the human body.
h) The doctor took my temperature using a thermometer.
Test yourself
Answers
1.
2.
3.
4.
5.
Good
a) Air will be trapped between the layers, air is a good insulator
b) Newspaper prevents the cold from the floor affecting the temperature of the bed;
newspaper is an insulator
c) The wool traps air between its long fibres; air is a good insulator
d) The holes trap air; air is a good insulator
Yes, it will be effective.
•
Silver reflects heat and this prevents the heat from entering the gallery.
•
Foam is an insulator.
•
Wood is an insulator.
•
The crinkles provide more surface area to reflect heat.
a) It does not require energy input from a source. Therefore, there is no heat loss.
b) Lighter materials, more streamlined, sufficient lubrication to turn the pedals easily
Cover them with an insulator, for example, a geyser blanket
(1)
(2)
(2)
(2)
(2)
(5)
(2)
(3)
(1)
Total: 20
Topic 12: Insulation, energy saving and energy transfer to the surroundings
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TOPIC 13: THE NATIONAL ELECTRICITY SUPPLY SYSTEM
Topic overview
This topic deals with the national electricity supply system in South Africa. It looks at how energy in
different resources is converted into electrical power. Learners will need the knowledge gained in the
previous topics to understand the energy transfers in power stations. They need to be able to follow the
sequence from the energy released by a source until it delivers electricity where it is needed. Learners need
to be familiar with the function of turbines, generators and dynamos in the production of electricity.
Electricity is in short supply in South Africa, and has become very expensive; learners investigate ways in
which energy can be conserved in the home.
Common errors learners make
Learners often mix up the sequence of how electricity is generated. Use a flow diagram on the board to
help them understand the process in each type of power plant.
Resources for this topic
•
•
•
Pictures of how electricity is generated in a power station, carried to the wires of the supply grid, and
carried to the electrical appliances in the home.
Video clips from the Internet showing how electricity is produced.
— http://www.youtube.com/watch?v=SeXG8K5_UvU
— http://www.youtube.com/watch?v=GI7AhajfhWE&feature=related
— http://www.youtube.com/watch?v=RILXhz8hzlE&feature=related
— http://www.youtube.com/watch?v=20Vb6hlLQSg&feature=related
An example of a dynamo or pictures of how they are used.
Starting off
Teaching guidelines
Learners must be familiar with the different types of energy and energy transfers. As an introduction,
start the topic off with a quick brainstorm of types of energy and what happens during energy transfers.
The conclusion that should be drawn is that energy is often wasted or lost as heat energy.
Activity 1: Revise knowledge on energy transfers
LB page 181
Answers
1.
2.
3.
4.
5.
6.
90
Non-renewable energy sources cannot be replaced in our lifetimes, as they take millions of years to
form. For example: coal, gas and oil. Renewable energy sources can be replaced and therefore cannot
be used up. For example: wind, solar and falling water power. Learners only have to give one example
of each.
Coal
There is a lot of steam coming out of the cooling towers, which means that ‘waste’ heat is being
released into the environment.
People will not live near a coal power station due to the pollution from the burning coal, which is
harmful to our health. The smoke can cause respiratory diseases.
Heat energy
Electrical energy
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Unit 1: Energy transfers in the national grid
Teaching guidelines
Learners may need to refer back to earlier topics on sources of energy, potential and kinetic energy and
energy transfers to surroundings to help them understand the information in this unit. Visit the websites
listed under Resources for this topic to show them video clips of power generation. Learners need to be
able to interpret diagrams of various aspects of electricity generation. Refer them to Figures 2 and 3 to
help them answer the questions in Activity 2. If possible, bring in a bicycle dynamo to demonstrate to the
class how a dynamo works. If one is not available, use Figures 6 and 7 in the Learner’s Book to explain
how a dynamo works.
Activity 2: Interpret diagrams of energy flow through the national electricity grid
LB page 184
Answers
1.
2.
3.
4.
1: Boiler; 2: Turbine; 3: Generator; 4: Pylon
A. Energy is transferred from the coal to the water:
the heat energy of the water.
The potential energy of coal
B. Energy is transferred from the steam to the turbine:
the mechanical energy of the turbine.
The heat energy of the water
C. Energy is transferred from the turbine to the generator:
the electrical energy in the generator.
The mechanical energy of turbine
D. Energy is transferred from the generator to the electrical cables:
the electrical energy in the cables.
The electrical energy in generator
Energy is wasted at each point in the transfers, as well as along the lengths of the electrical cables.
Energy is wasted at each of these points as some of the energy is transferred into heat energy, which
is not available for use in the system. At points A and B, some of the steam escapes from the system
and is released into the atmosphere. At point C, the mechanical operation of the turbine generates
heat, as does the generator, so it is not used in the energy transfer. In our homes, energy is wasted as
heat from light bulbs and other appliances. Energy is also lost down the lengths of cables and wires as
heat.
Support for this unit
Tell learners to draw a flow diagram to show the production of electricity from coal using Figure 3 on
page 183 of the Learner’s Book.
Extension for this unit
Tell learners to use the principle of how electricity is produced from coal to draw flow diagrams of how
electricity is produced from nuclear fuels, falling water and wind.
Topic 13: The national electricity supply system
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Unit 2: Conserving electricity in the home
Teaching guidelines
This unit deals with conserving electricity. South Africa has a finite amount of coal. Therefore, it is
important to use alternative energy resources to generate power, and each person must reduce their
electricity consumption. This can be achieved through using energy wisely in the home. The Learner’s
Book gives a number of suggestions of how to reduce electricity. Before going through the examples
with the class, do Activity 3 and let the class brainstorm ideas of how they can reduce electricity in their
homes.
Activity 3: Brainstorm ways to use energy wisely
LB page 186
Answers
Learners’ answers will vary. They may be similar to the ideas given on page 186 of Learner’s Book.
However, give recognition to original ideas.
Activity 4: Tabulate a list of dos and don’ts for using energy wisely
LB page 187
Answers
Using energy wisely
Electricity Dos
Electricity Don’ts
1. Use energy-saving bulbs in light fittings.
5. Do not leave cellphone chargers plugged
in when not in use.
2. Switch off lights and appliances, such as radios and
TVs, when not in use.
3. Wear warm clothing rather than heat the house to keep
warm.
11. Do not put warm food in the fridge as the
fridge has to draw more electricity to get
cold again.
4. Stop cold draughts in the house by ensuring that doors
and windows are closed and sealed properly.
6. Shower instead of bath, as less hot water is used, which
means that less electricity is used in the geyser.
7. Turn off the geyser when not in use.
8. Boil the correct amount of water required in the kettle.
9. Use the correct plate on the stove to cook food.
10. Use the correct size fridge for your family.
12. Hang up clothes to dry rather than use the tumble drier,
where possible.
13. Use blankets for warmth instead of heaters and electric
blankets.
14. Cover the geyser with a geyser blanket to reduce loss of
heat.
15. Place insulation in ceilings to reduce heat energy loss
through the roof.
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Extension for this unit
Ask learners to work in pairs to make a poster or information booklet on how the public can reduce
energy use in their homes. They can use pictures from magazines to illustrate their ideas.
Skills focus: Conducting a survey
Teaching guidelines
This valuable Skills Focus section will prepare your learners for data handling tasks in the future.
Conducting a survey and designing a questionnaire are important skills to have, and the activity that
follows allows the learners to practise these in the context of energy sources. A good way to introduce the
importance of a well-designed questionnaire, might be to conduct a small (non-energy related) survey in
the class, using deliberately misleading or poor questions (such as ‘What mark did you get for your last
test?’ or ‘Do you think that too many cars on the road pollute the environment too much, and therefore
should be banned?’) and then let the class analyse how the questions could have been phrased differently
to obtain better results to work with.
Activity 5: Practise conducting a survey on energy sources used
LB page 188
Answers
The answers to this activity will vary, depending on individual learners’ questionnaires. However, note the
following points when marking this activity:
•
Ideally, the learners should conduct their surveys in the community, but if this is not possible, then let
them conduct their surveys within the school (teachers and learners from other grades).
•
The graph should be neat and accurate, and feature a heading and labels on the axes.
•
The learners’ written answers must reflect their survey findings, and need to be substantiated and
explained adequately.
Topic 13: The national electricity supply system
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TOPIC 13 REVISION
LB page 190
Science language activity
Answers
1.
2.
3.
4.
5.
National electricity grid
Pylon
Turbine
Generator
Dynamo
Test yourself
Answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
Coal
(1)
Nuclear, hydropower or wind power (any two)
(2)
the heat energy from the burning coal heats water and turns it
Coal is burnt in power stations
the energy in the steam makes the turbine turn to produce mechanical energy
into steam
the turbine is connected to a generator, which converts the mechanical energy into electrical energy
the electricity produced is fed into the national electricity grid and taken to our homes via
cables.
(8)
National electricity grid
(1)
No, energy is lost at each stage of energy transfer in the system, often as heat energy.
(2)
Tumble dryer, vacuum and kettle.
(3)
Tumble dryer: 4 000 W; vacuum: 2 500 W; kettle: 2 000 W.
(3)
Hang up clothes to dry and only use the tumbledryer when it is really necessary. Parts of the house
can be swept manually rather than cleaned with the vacuum. Only put the required amount of water
in the kettle and keep hot water in a flask.
(3)
Appliances are not 100% efficient because some energy is always wasted as heat to operate the motors
in the appliance.
(2)
Total: 25
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TERM 3 PRACTICE TEST MEMORANDUM
LB page 191
1.
a)
b)
c)
D
C
B
(1)
(1)
(1)
2.
a)
b)
Radiation
Convection
(1)
(1)
3.
a)
b)
c)
d)
e)
E
D
A
C
B
(1)
(1)
(1)
(1)
(1)
4.
Energy cannot be created or destroyed. It can only be transferred from one form to another.
5.
a)
b)
6
a)
b)
(1)
Renewable energy is readily available, so it will not run out. Non-renewable energy sources will
run out.
(2)
Potential energy is stored energy and kinetic energy is movement energy.
(2)
When the boy is holding the ball, it has potential energy. As soon as the ball is dropped, the
potential energy is converted to kinetic energy. When the ball bounces back, the kinetic energy is
converted to potential energy.
(3)
The speed of the ball will be greatest just before it hits the floor. This is when the ball will have
the most kinetic energy.
(2)
7.
a)
b)
c)
d)
e)
Conductor
To show that metals (solids) transfer heat by conduction.
Metals are good conductors of heat.
Metal pots are used to cook food because they conduct heat very well.
Eventually, all the paper clips will melt off the rod.
8.
a)
Useful energy = 1 540 J + 600 J = 2 140 J
Wasted energy = 660 J
(3)
The hairdryer wastes more energy. For both appliances, kinetic energy and heat energy is useful
and sound energy is wasted. The hairdryer produces more sound energy.
(2)
b)
(1)
(1)
(1)
(1)
(1)
Total: 30
Term 3 Practice test memorandum
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TERM 4
Within Term 4, your Grade 7 learners will cover the following sections of content:
Strand
Topics and time allocation
Unit
LB page
Planet Earth
and Beyond
14 Relationship of the Sun to
Earth
Unit 1: Solar energy and Earth’s seasons
194
Unit 2: Solar energy and life on Earth
202
(14 hours)
Unit 3: Stored solar energy
206
15 Relationship of the Moon
to Earth
Unit 1: Relative positions of the Moon and
Earth
212
(7 hours)
Unit 2: Gravity
214
Unit 3: Tides
218
Unit 4: Tides and ecosystems on the shore
222
Unit 1: Early indigenous knowledge
228
Unit 2: Modern developments
236
16 Historical development of
astronomy (7 hours)
TERM 4 ASSESSMENT
The following Formal Assessment Tasks will need to be completed in Term 4. You may use the examples
in this book for the learners or you may want to develop your own.
96
Formal assessment
Mark allocation
Learner’s book
page
Teacher’s guide
page
Practical task: Use diagrams to write about
and explain the effects of the Moon’s
gravity on Earth, showing the tides
30
224
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TOPIC 14: RELATIONSHIP OF THE SUN TO EARTH
Topic overview
In this topic, learners find out about the tilt of Earth’s axis, and how this affects the intensity of solar
energy received at different places on Earth, as well as seasonal differences in the length of day and night
in each hemisphere. They also consider in greater depth than in previous grades how solar energy sustains
life on Earth, focusing on how it is passed along the food chain and its role in the water cycle. They
learn how fossil fuels are formed, how they store energy from the Sun and why they are considered nonrenewable resources. Activities help learners to develop modelling, drawing and communication skills,
and a case study on fracking helps them engage with real issues regarding the strategies to expand South
Africa’s supply of natural gas.
Common errors learners make
Learners occasionally think that seasonal change happens because Earth is sometimes nearer and
sometimes further away from the Sun in its orbit. Explain to them that these differences in distance are
very small compared with the overall distance of Earth from the Sun, and help them see how it is in fact
the constant tilt of Earth as it revolves around the Sun that causes these changes.
Resources for this topic
•
•
•
•
•
Textbooks
Globe: one for the class
Ball: one per learner or pair of learners
Torch: one per pair of learners
Pictures, video clips and animations from the Internet showing:
— Earth’s passage around the Sun
— the changing amounts of solar energy reaching different parts of Earth throughout the year
— how coal, oil and gas are formed from the Sun’s energy
Starting off
Activity 1: Think about what you know about the Sun
LB page 193
Answers
1.
2.
3.
4.
5.
6.
The Sun/their food
herbivores
carnivores
Green plants
There would no light, no warmth, no liquid water, no rain and no food.
Summer
Winter, spring and autumn
Depending on where you live, summer and winter can be wet or dry. For example, Cape Town is wet
in winter but Johannesburg is dry.
Topic 14: Relationship of the Sun to Earth
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Unit 1: Solar energy and Earth’s seasons
Teaching guidelines
This is a long unit, which builds learners’ understanding of why temperature and the length of day change
with the seasons. Work through it systematically, facilitating the practical activities to help learners build
understanding. If necessary, demonstrate the revolution of Earth on a tilted axis and the effects of this
using a globe. The diagrams in the Learner's Book are important. The text in the diagrams is intended to
help learners interpret the information in them, so encourage them to read the labels when they look at
the diagrams. Where possible, set up a model a the globe to support understanding.
Activity 2: Make a model of the globe using a ball
LB page 195
Answers
Check that learners’ models show the equator around the circumference of the ball, that the north and
south poles are correctly positioned, and that the hemispheres are correctly labelled.
Activity 3: Demonstrate the passage of Earth around the Sun
LB page 197
Answers
1.
Hemisphere titled toward
the Sun
Hemisphere tilted away
from the Sun
Hemisphere not tilted
toward or away for the Sun
Position 1
southern hemisphere
northern hemisphere
-
Position 2
-
-
both hemispheres
Position 3
northern hemisphere
southern hemisphere
-
Position 4
-
-
both hemispheres
2.
98
a)
b)
c)
d)
No
It tilted away from the Sun.
It tilted towards the Sun.
Positions 2 and 4
Term 4
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Activity 4: Draw and label diagrams to show the tilt of Earth and the direct and
oblique rays of sunlight energy that cause the four seasons
LB page 201
Answers
1–3.
N
circle of illumination
Earth’s axis
oblique rays
direct rays
It is summer in the southern
hemisphere. The date is around
21 December. Days are longer
than nights.
0° latitude
(equator)
S
This side of Earth is
experiencing night.
The tilt of Earth and the seasons in the southern hemisphere
Support for this unit
To help learners understand how the same amount of energy spread over a larger area results in less
energy per unit area do the following: Take a slice of bread and a half a slice of bread; spread the same
amount of jam or butter over each. Ask learners on which piece of bread there will be more jam or butter
in each square centimetre (or bite!).
Unit 2: Solar energy and life on Earth
Teaching guidelines
Learners have been introduced to some of the key concepts in this unit in previous grades. Help them link
to that knowledge as you work though the unit by asking questions about it. They will learn about both
photosynthesis and food chains in more detail in Grade 8, so this unit does not go into as much detail
with regard to either of these topics as is done there. The emphasis here is on the importance of solar
energy in sustaining life, so help learners to focus on that.
Topic 14: Relationship of the Sun to Earth
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Activity 5: Draw a diagram of photosynthesis
LB page 202
Answers
1.
Water
Light energy from
the Sun
Carbon dioxide
Photosynthesis
Glucose (food)
Oxygen
Activity 6: Write about how the Sun’s energy supports life on Earth
LB page 205
Answers
1.
a) Life on Earth needs energy from the Sun to survive. Plants use light energy to make food. Energy
is passed along the food chain when herbivores eat plants, and are in turn eaten by carnivores. The
Sun’s energy warms the air, the land and the water of Earth. It keeps the water cycle going by
causing water to evaporate and preventing it from freezing.
b) Life on Earth is supported by the Sun’s energy.
Extension for this unit
Learners could try to construct a food chain from plants and animals that they are familiar with.
Unit 3: Stored solar energy
Teaching guidelines
Work through the information on the process in which fossil fuels are formed with the learners, referring
to the text and pictures in the Learner’s Book. You might like to draw a framework for the flow diagram
on the board for learners to follow (Activity 7). Stress the flow of energy from the Sun right through
to the fossil fuel. It would work best drawn vertically in their books. Remind learners of the structure
of a good paragraph and give feedback while they are writing their paragraph in Activity 8. Facilitate
discussion about the differing points of view on the issue of fracking.
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Activity 7: Draw and label a flow diagram to show energy flow from the Sun
through to fossil fuels
LB page 207
Answers
The correct sequence is:
•
Plants use light energy from the Sun to make their own food.
•
Herbivores eat plants and the Sun’s energy passes to them.
•
Carnivores eat herbivores and the Sun’s energy passes to them.
•
Plants and animals die.
•
Plant and animal remains are deposited under water.
•
The remains of dead plants and animals are covered by layers of mud and soil.
•
Pressure from layers of soil and mud changes the plant and animal remains into coal, oil and gas.
•
Coal, oil and gas contain energy from the Sun that was first absorbed by plants.
Activity 8: Answer questions about fracking
LB page 209
Answers
1.
2.
3.
4.
5.
It will supply South Africa with much-needed gas. Jobs will be created in the mining, construction
and transport industries in particular.
People who are opposed believe that it will use up scarce water resources, pollute water and spoil the
beautiful scenery of the Karoo. They also believe that the benefits will be short-lived, but the damage
will last forever. They believe that no additional jobs will be created as many jobs will be lost in
farming and tourism.
The paragraph should have a clear topic sentence which expresses the learner’s view. Supporting
arguments should be given, and should be well linked to each other.
a) Learners’ drawings should show the key steps as described in the Learner’s Book, with
appropriate labels, such as those given on pages 206 to 207. Check that they have matched the
labels to the drawings correctly, and that the sequence of steps is correct. They do not have to
draw identical drawings, and labelling might differ but the information must be correct.
b) Learners should write about the fact that energy from the Sun is used by green plants to make
food; the energy is passed along the food chain as herbivores eat plants and then carnivores eat
herbivores. This energy is still in the animals when they die, and so is part of their remains that
are buried by layers of mud and soil, and form fossil fuel. When we burn fossil fuel, we are using
this stored energy.
Many different answers are possible – solar energy, wind energy, hydropower or nuclear energy: use
less energy so that reserves last longer; import gas and other fossil fuels from elsewhere
Extension for this unit
Ask learners to help you collect up-to-date information about the fracking proposals in the Karoo from
newspapers, magazines and TV to share with the class.
Topic 14: Relationship of the Sun to Earth
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TOPIC 14 REVISION
LB page 210
Science language activity
Answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
Earth’s revolution is the movement of Earth around the Sun.
A planet’s orbit is the fixed pathway it follows as it revolves around the Sun.
Radiation is the way in which energy travels through space.
The circle of illumination is the line dividing the lit from the dark half of Earth.
An axis is an imaginary line though the centre of Earth, from the North Pole to the South Pole.
When something is tilted it is at an angle, not straight.
The intensity of solar energy is the amount of solar energy per unit area that reaches a place.
Photosynthesis is the process in which plants use light energy from the Sun to make their own food.
Fossil fuels are fuels made from the remains of plants and animals that lived
long ago.
Test Yourself
Answers
1.
2.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
a)
b)
c)
d)
The tilt of Earth’s axis means that we have seasons.
The intensity of the Sun’s energy is greater when the Sun’s energy is direct.
Day is never longer than night at the equator.
In summer, days are longer than night because of the tilt of Earth’s axis.
Plants use light energy from the Sun to make their own food.
The Sun provides energy to plants, herbivores and carnivores.
The Sun’s energy is stored in fossil fuels.
In the water cycle, the Sun’s energy is used for evaporation.
Coal forms from the remains of dead plants.
Fossil fuels are a non-renewable source of energy.
(10)
Check that the learners diagrams show the Sun, Earth, equator and axis. The axis should be
tilted so that the Southern Hemisphere is titled toward the Sun.
(4)
Winter
(1)
Check that learners have drawn rays parallel, and equal size (thickness) in both hemispheres,
with labels to note equal amounts of solar energy. Labels must include: oblique and direct rays;
bigger/smaller angle (award half marks to get 2 marks for each hemisphere)
(4)
Check that the learners diagrams indicates a smaller area of heating in southern hemisphere and
a larger one in Northern Hemispher; that labels draw attention to this, and also link area of heating to greater intensity in Southern Hemisphere, and lower intensity in Northern Hemisphere. (6)
Total: 25
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TOPIC 15: RELATIONSHIP OF THE MOON TO EARTH
Topic overview
In this topic, learners begin by revising what they have learnt previously about the movement of the
Moon around the Sun and the phases of the Moon. This is relevant in the understanding of tides later
in the topic. They find out about gravity, and how it affects the Moon and Earth. They also learn how
the Moon and the Sun cause the tides, finding out that the effect of the Moon is more noticeable than
the effect of the Sun, though the latter is significant at Full and New Moon, when spring tides are
experienced. The rise and fall of the water levels associated with tides affects ecosystems on the shore, and
learners find out how physical conditions change with the rise and fall of the tide, and how these affect life
in the intertidal zone. Learners carry out a practical investigation to help them understand how gravity
keeps Earth in orbit, and do a practical task to develop their understanding of the causes of tides and
their regular occurrence. This task focuses on interpreting pictures and drawing diagrams, an important
skill that learners need to help them communicate what they understand. In addition, a Skills Focus task
(conducting research) is also carried out.
Common errors learners make
Learners sometimes think that a larger body will have a greater mass than a smaller body. Help them
understand that it is the amount of matter in an object that affects its mass, not its size. For example, an
iron ball and balloon of the same size will not have the same mass – the mass of the iron ball is much
greater than that of the balloon. In the Solar System, however, the largest objects – the Sun and the gas
giants, do have the greatest mass – partly because they are so much bigger than other objects.
Resources for this topic
•
•
•
•
•
•
•
Textbooks and reference materials
Globe
Ball – one per learner/pair of learners/small group
Shopping bag/string bag – one per learner
Thick string/thin rope – about one metre per learner
Video clips/animations from the Internet showing:
— the Moon in orbit around Earth
— how the gravitational pull of the Moon results in ocean tides on Earth
— how the gravitational pull of the Sun at Full Moon and New Moon causes spring tides
Video clips, pictures and texts about shoreline ecosystems
Starting off
Teaching guidelines
Learners have been introduced to the movement of the Moon around Earth, and phases of the Moon
before. However, they have not been introduced to the topics of gravity and tides previously. When you
take answers to the questions, help them draw on prior knowledge for Question 1, and explain that they
will learn about the answers to Question 2 in this topic – they should make sure they can answer these
questions by the end of the activity.
Topic 15: Relationship of the Moon to Earth
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Activity 1: Revise knowledge about Earth and the Moon
LB page 211
Answers
1.
2.
3.
a) Orbits
b) They are each held in place by gravitational forces.
a) The Sun
b) Half
c) All of it
d) Full Moon
It causes the tides.
Unit 1: Relative positions of the Moon and Earth
Teaching guidelines
Navigate the content of this unit with the learners, using the text and illustrations to support their
learning. Spend some time helping learners understand that Figure 3 is showing the Moon in different
positions in its orbit, and how in each position, a different part of the lit part of the Moon can be seen
from Earth. Pay partial attention to the position of the Moon in relation to the Sun and Earth. Pay
particular attention to the position of the Moon relative to the Sun and Earth at Full and New Moon, as
these are important for work on spring tides done in Unit 3.
Activity 2: Draw the Moon in four positions and identify its phase in each
LB page 213
Answers
2.
3.
4.
Label phases: Full Moon, New Moon, Third Quarter, First Quarter
Colour in the dark side of the Moon for each phase.
a) New Moon
b) Full Moon
Support for this unit
When studying Figure 3, learners could use a small piece of paper to block the part of the moon not seen
from Earth in each of its positions, i.e. the part of the Moon outside the line of the orbit. This will help
them see the shape of the lit part visible from Earth, which shows the shape of the phase in that position.
Unit 2: Gravity
Teaching guidelines
•
•
•
104
Gather the resources learners will need for Activity 3.
Work though the relationships that affect the gravitational attraction between two objects carefully.
Help the learners to see that it is both mass and distance that are important. If two objects have large
mass, the gravitational pull they exert on each other will be greater than if they are both of small
mass, or if one of them has small mass. When two objects are close, the gravitational pull they exert
on each other will be greater than when they are far apart.
Help the learners see from the diagrams how the gravitational pull of the Sun keeps Earth in its orbit
around the Sun because it is has more mass than Earth.
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Activity 3: Demonstrate the pull of gravity
LB page 216
Answers
1.
a)
b)
c)
d)
e)
f)
g)
Earth
The Sun
The pull of gravity
Earth’s orbit around the sun
It would fly off into space in a straight line.
It would happen because there would be nothing pulling it in towards you, keeping it moving in
an ‘orbit’.
Gravity keeps Earth moving around the Sun in a circular orbit.
Extension for this unit
Ask learners to think about what happens to anything they ever drop. Where does it go, and why? They
should be able to answer that it falls to Earth, and that this is because of the gravitational attraction
between Earth and the object. Because Earth has a much greater mass than the object, the object will
move towards Earth.
Unit 3: Tides
Teaching guidelines
•
•
•
•
•
•
Depending on where your school is located, ask the learners if any have been to the sea or the beach.
Did they find the water level the same each time they went? Ask them to share their observations and
experiences.
Spend some time looking at the pictures of the same scene at high and low tide. Encourage the
learners to look for evidence that shows difference in the water levels.
Explain that the water level changes like this in a regular pattern. We can predict when it will be high
and when it will be low tide. Then work through the information in the introductory paragraph in the
unit to help them link these concepts to the terms for them.
Move on to the explanation of the changing levels of water – the tides, using the text and diagrams to
help learners understand the effect of the gravitational pull of the Moon on the water of Earth.
Refer to the work done in Unit 1 to help the learners understand why there are spring tides only every
two weeks.
There is no activity in this unit because the practical task is based heavily on it. You could ask
learners to start work on it before they engage with Unit 4.
Extension for this unit
CAPS does not require that learners study neap tides. However, learners might like to know about the
influence of the Sun on the tides when it is at right angles to the moon – at First and Third Quarter.
You could ask them to suggest what the tides might be like in these phases. In these phases, the Sun’s
gravitational pull on Earth is at right angles to the pull of the moon. As a result, the high tide will be
lower than usual, and the low tide higher. These lower than usual high tides and higher than usual low
tides are called neap tides.
Topic 15: Relationship of the Moon to Earth
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Skills focus: Conduct research
Activity 4: Practise conducting research
LB page 221
Answers
1.
a)
b)
c)
d)
Answers will vary. Check that the questions will reveal to relevant information on the topic.
Some questions could include: Are people and their activities affected by the tides? What are the
effects? How are animals affected by the tides? How are plants affected by the tides? Do the tides
only affect life close to the sea, or can other places be affected?
Learners will write down different things, depending on their previous knowledge.
Sources can include the Learner’s Book (Unit 4), the Internet (encourage learners to discuss the
key words they will use for their research), reference books in the library or that they have at
home, experiences of people they know who live by the sea and their own observations.
Answers will vary.
Unit 4: Tides and ecosystems on the shore
Teaching guidelines
Refer learners to the pictures in Unit 3, which show the shore at high and low tide. Help them to identify
the area between the two water levels - and tell them that this is called the intertidal zone: the area of
shore between the high and low tide levels.
Discuss with them how water seldom reaches the shore above the high water level – only perhaps at
spring high tide, and when there are very heavy storms.
The area below the low tide level is always under water. The shore in the intertidal zone is covered in
water at high tide, and bare at low tide.
Ask them to think about how these changes affect the physical conditions there – temperature and
moisture in particular, and discuss their ideas. Explain that these changes affect plants and animals in the
shoreline ecosystems. Then work though the text in the Learner’s Book with them.
Activity 5: Describe shoreline ecosystems
LB page 223
Answers
1.
2.
3.
Sandy shore and rocky shore ecosystems
Challenges include: dry and hot conditions when the tide is out; very wet conditions/being submerged
in water when the tide is in; cold water
It brings in food from the sea. Low tide and shallow water allow light to reach plants growing in rock
pools.
Support for this unit
If possible, show learners additional pictures and video clips about the shoreline animals and plants, and
how they are affected by the changing levels of the tides.
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FORMAL ASSESSMENT
Practical task: Use diagrams to write about and explain the effects
of the Moon’s gravity on Earth, showing the tides
LB page 224
Teaching guidelines
•
•
•
•
Explain to the learners that the information they need to complete this task is contained in Units 3
and 4 – they should refer to these to help them.
Decide if the work will be done in class, or for homework.
Set deadlines by when the work must be completed. It might be helpful to suggest a date for each
question so that the task is not overwhelming or left to the last minute.
Learners should be allowed to discuss their ideas with their peers, but must produce their piece of
written work on their own.
Assessment tool
Mark the work, using the answers and suggested mark allocations below:
1.
a)
b)
c)
d)
2.
Figure 18(a) shows low tide; Figure 18(b) shows high tide.
(1)
The answer must demonstrate that learners can see that the water level is higher in Figure 18(b)
than in Figure 18(a), and therefore that must be high tide. (Possible answers include: The water is
higher up the shore in Figure 18(b); the water is lower down the shore in Figure 18(a); people are
walking in Figure 18(a) where the water covers the sand in Figure 18(b).)
(1)
In Figure 18(a), the water level will be even lower; less of the beach will be covered by water; in
Figure 18(b) the water level will be even higher; more of the beach will be covered by water. (4)
In Figure 18(b), animals and plants will be submerged in water; gradually the water level will
drop, until six hours later, it will be low tide; plants and animals will be in the air – and could
get too hot or dry out. Then the tide will rise again over the next six hours, bringing food to the
intertidal zone. (Any four points)
(4)
Award marks for the drawing as follows:
a) Moon and Earth both round, and Earth bigger than Moon
b) Half a mark for each correctly drawn and labelled tide, as in model answer
c) Half a mark for arrow depicting gravitational pull, half a mark for label
(1)
(2)
(1)
3.
a)
b)
c)
d)
Correct heading, Moon and Earth round and correctly sized
P, Q, X and Y in the correct places
Each low and high tide must be correctly drawn and labelled
Correct arrow direction, Moon’s gravitational pull label
(1)
(2)
(2)
(1)
4.
a)
b)
12 hours
The Earth has rotated through half a rotation. Place X is now on the opposite side of the
Earth to the moon. The Moon’s gravitational pull pulls Earth and the water at X towards it.
Earth does not move as much as the water. As a result, the water bulges away from Earth,
causing high tide.
(1)
Sun correctly positioned
Insert arrow and label Sun’s gravitational pull.
Tides will be higher than usual at X and lower at C.
(2)
(1)
(2)
5.
a)
b)
c)
(4)
2
[30 × 3 = 20]
Total: 20
Topic 15: Relationship of the Moon to the Earth
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Support for learners with barriers to learning
If you have any learners who have visual difficulties, make them enlarged versions of the task to assist
them in seeing the pictures and the diagrams, and in reading the text.
TOPIC 15 REVISION
LB page 226
Science language activity
1.
2.
3.
4.
5.
6.
7.
8.
9.
A moon is a rocky body that revolves around a planet.
A phase of the Moon is the shape of the lit part of the moon as seen by an observer on Earth.
Gravity is the tendency of all objects to attract, or pull towards, each other because of their mass.
Mass is the amount of matter in an object.
An astronaut is a person who travels into space.
A geologist is a scientist who studies rocks.
Tides are the predictable, repeated rise and fall of sea and ocean levels.
At high tide, the water level is higher than usual.
Spring tide is the tide when high tide is extra high and low tide is extra low.
Test yourself
Answers
1.
a)
b)
c)
d)
e)
f)
g)
h)
i)
2.
a)
b)
c)
d)
Objects of large mass exert more gravitational pull on each other than objects of small mass.
The closer together two objects are, the greater the gravitational pull that they exert on each other
will be.
The Earth’s gravitational pull keeps the Moon revolving around Earth.
Spring tides are experienced when the Sun, Earth and Moon are aligned with each other.
There is a high tide at the same place about every twelve hours.
On a beach, animals between the high and low water levels have to cope with periods of dry and
wet conditions.
The Moon has less gravitational pull than Earth because it has less mass.
Tides are most noticeably affected by the gravitational pull of the Sun at both Full Moon and
New Moon.
Without the pull of the Sun’s gravity, the Earth would fly into space.
(10)
The learners’ diagram must show Earth between the Sun and the Moon, and each must be
labelled.
The side of the Moon and Earth facing away from the Sun must be shaded.
The water must bulge towards the Moon. Low and high tides must be labelled.
Spring tides
(3)
(2)
(4)
(1)
Total: 20
108
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TOPIC 16: HISTORICAL DEVELOPMENT OF ASTRONOMY
Topic overview
The first unit of this topic reviews the early indigenous knowledge of astronomy. Learners will come to
understand how the early inhabitants of Earth observed the predictable patterns of the Sun, Moon and
stars and used them to measure time, develop calendars, find direction, plan their farming and celebrate
special holy days. The second unit examines modern developments in astronomy, highlighting the
important discoveries by Copernicus, Galilei, Kepler and Newton.
Common errors learners make
It is very important that you tell the learners never to look directly at the Sun. Doing so will damage their
eyesight permanently. Similarly, telescopes or binoculars should never be used to view the Sun either.
(Although the sun could be viewed directly or with an instrument at sunrise and sunset, it is better to
discourage this practice in general for safety reasons.)
Resources for this topic
•
•
•
•
•
•
•
Binoculars and telescopes if at all possible, even cheap children’s binoculars will be useful
Reference materials on significant discoveries relating to astronomy
A visit to a local observatory for the class, or a night outing to go stargazing.
Johannesburg Planetarium: Tel 011 717 1392 http://www.planetarium.co.za
Iziko Planetarium (Cape Town): Tel 021 481 3800 http://www.iziko.org.za
South African Astronomical Observatory (Cape Town): Tel 021 447 0025
The primary SAAO observation facility is in Sutherland, Northern Cape. It has the largest single
optical telescope in the southern hemisphere and fifth largest in the world: Tel 023 571 1205
http://www.salt.ac.za/
Starting off
Teaching guidelines
Some things in the night sky are brighter than others. Astronomers use a system of magnitude to describe
the brightness of objects. Most objects are assigned positive numbers: the larger the number, the dimmer
the object (magnitude 3 is dimmer than magnitude 2). Very bright objects are assigned negative numbers:
this is true of the Sun, the Moon, bright planets and the brightest stars. Here are a few examples:
Magnitude –27
The Sun
Magnitude –12
The full Moon
Magnitude –5
Venus (the brightest planet) at its brightest
Magnitude –1
Sirius and Canopus (the two brightest stars)
Magnitude 6
The dimmest objects visible with the naked eye
Magnitude 10
The dimmest objects visible with binoculars
Magnitude 25
The dimmest objects on a photographic plate
produced with a large telescope
Source: Adapted from http://www.umich.edu/~lowbrows/guide/eye.html. This page has a variety of
suggestions for budding amateur astronomers who wish to observe the sky with only the unaided eye.
Topic 16: Historical development of astronomy
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Activity 1: Observe the night sky
LB page 227
If possible, arrange a class outing for stargazing. If you are unable to use a site of higher altitude, find an
open area such as a school field. You could try to arrange a visit to an observatory or find photographs of
the three most visible constellations in the Southern Hemisphere.
Answers
3.
Stars twinkle because they are burning balls of gas. Planets are made of rock and therefore only
reflect light and do not twinkle.
Unit 1: Early indigenous knowledge
Teaching guidelines
Solstices and equinoxes were important elements in the predictable patterns in the sky observed by early
people. Ensure that the learners understand what they are. Both of these terms refer to the path of the
Sun throughout the year:
•
The equinox is either of the two days or periods each year when the Sun is directly overhead at the
equator and day and night are of equal length. In the Southern Hemisphere, the spring (vernal)
equinox happens around September 22/23 and the autumn equinox occurs around March 20/21.
•
In the Southern Hemisphere, the winter solstice occurs when the Sun is directly overhead the Tropic
of Cancer (June 21/22) and we experience the longest night and shortest day. The summer solstice
occurs when the Sun is directly above the Tropic of Capricorn (December 21/22) and we enjoy our
longest day and shortest night.
Activity 2: Write about traditional cultural interpretations
LB page 228
Answers
1.
2.
3.
Early people did not have light pollution to affect their magnitude (other than firelight), so they were
able to see many celestial objects. They also spent a great deal of time viewing the skies and noticed
changing patterns because they spent most, if not all, of their time outside hunting, tending to cattle
or telling stories around the fire. (Accept any other suitable answers.)
Accept any suitable answers, including finding direction, deciding when to plant and to mark special
holy days and festivals.
a) Constellations are groupings of stars that are named by astronomers.
b) The ecliptic is the path across the sky that the Sun appears to travel on over the course of a year.
c) The zodiac is a circle of twelve constellations that can be seen at certain times of the year.
Activity 3: Draw diagrams to explain different time periods
LB page 230
Answers
The learners are to draw simple diagrams to illustrate and expand their description of the different types
of years.
1. Solar year/calendar year: The time period of a year includes the four seasons and it is commonly
based on the solar year, which is the orbital period of Earth moving around the Sun over 365 days.
Lunar year: It has about 354 days and consists of twelve full cycles of the phases of the Moon.
(Learners may draw modified sketches of the phases of the moon – they must note that twelve lunar
cycles comprise one lunar year.) Note: lunar calendars may be found at www.moonconnection.com
Seasonal year: The time period between successive recurrences of a seasonal event, such as the
flooding of a river or the migration of a species of bird.
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2.
3.
Learners should recall the phases of the lunar cycle from Topic 15, Unit 1. Their answers should
illustrate their knowledge that the lunar phases are created by the changing angles (relative positions)
of Earth, the Moon and the Sun, as the Moon orbits Earth:
— New Moon – not visible as there is no sun shining on the side we see (dark moon) and is only
viewable after sunset
— First Quarter – Left half visible and can be seen in the afternoon and early evening
— Full Moon – the whole Moon is visible and appears sunset to sunrise (the whole night)
— Last Quarter – Right half visible and it can be seen late at night or in the morning
Each phase should have an accompanying diagram.
Figure 5 on page 230 will provide clues. The earliest methods of telling time were to put a stick in the
ground and watch the shadow as the Sun moved across the sky. As the Sun always rose on the same
side and set on the opposite side, it was a relatively constant motion and could be measured. Early
people learnt to tell how much of the day was left by looking at the length of the shadow and they
could make marks in the dirt to keep track of this.
Activity 4: Apply indigenous knowledge with investigations and practical work
LB page 232
Answers
1.
2.
The learners need to do this practical activity on a new moon at home at night.
Learners can either use the stories on the resource pages and other material in the Learner’s Book
or do further research themselves. Their text must consist of traditional cultural interpretations and
stories that are used to pass on information about the predictable patterns of:
a) the stars
b) the Moon
c) the Sun.
Extension for this unit
Learners can make their own sundials using an ice cream container,
sand, a flat piece of wood, dowelling and some modelling clay.
1. Put the lump of modelling clay in the middle of the bottom of
the ice cream container and fill the container with sand.
Make a hole in the middle of the lid and put the lid back on
tightly.
2. Put the container in the middle of the flat piece of wood
somewhere that gets the sun at all times of the day.
3. Poke a piece of dowelling through the hole in the lid, pushing it
down so that it sticks in the modelling clay. This part of the sundial is called the ‘gnomon’.
4. Put some modelling clay between the stick and the hole in the container to keep it steady.
Every hour, on the hour, mark where the shadow falls on the wood and write the time next to
the mark.
Are the marks even? The marks will be different distances apart at different times of the day, because
Earth is tilted on its axis. The next day, use the sundial to guess the time.
The learners can also use their own bodies as sundials, as this picture of an analemmatic sundial
illustrates. An analemmatic sundial is a horizontal sundial that does not have hour lines marked on it.
Instead of hour lines, it has a series of fixed hour points that are located in a half-circle pattern around
the analemma. A person standing on the analemma will cast a shadow, which will pass through the hour
markers.
Topic 16: Historical development of astronomy
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Unit 2: Modern developments
Teaching guidelines
The learners have been taught that Earth is round, that it rotates and that it orbits the Sun. This may
make it very difficult for some of them to understand the thinking and incorrect assumptions of early
astronomers. Remind the learners that early astronomers believed the Sun moved around Earth, and that
they did not have the powerful telescopes we have today to see beyond the Solar System. The easiest way
to understand how early astronomers saw the heavens is to spend a few hours stargazing.
Activity 5: Answer questions on the Copernican model
LB page 237
Answers
1.
2.
3.
From Earth, it appears as though the sky is full of brightly lit objects that are in constant motion
around us, while Earth is a mass of rock and water that feels stationary.
He was incorrect, but early astronomers couldn’t see further than the Solar System, so they thought it
made up the ‘universe’. Today we know that the Solar System is just one of many galaxies.
No, his observations were limited by his eyesight and the instruments of the day. From Earth, there
is no depth perception and all the stars appear to be an equal distance away. The distant planets and
stars do move but in their own unique orbits around the centre of their distant galaxies.
Activity 6: Research and write about Galilei’s discoveries in astronomy
LB page 238
Answers
1.
2.
Heliocentric model: an astronomical model where Earth and the planets revolve around the Sun as
the centre of the universe.
Geocentric model: an astronomical model where the Sun and planets move around the Earth and it is
seen as the centre of the universe.
The learners are to do further research on any one of Galileo Galilei’s discoveries and write a short
report explaining it in further detail. Provide them with reference materials to perform this task if
they are unable to access a public library or the Internet.
Activity 7: Answer questions about Kepler’s Laws of Planetary Motion
LB page 238
Answers
1.
2.
3.
112
Astrology consists of a number of belief systems, which hold that there is a relationship between
astronomical phenomena and events in the human world.
Astronomy is the scientific study of the universe and celestial bodies, especially their positions and
movements.
Qualitative: Connected with how good something is, rather than with how much of it there is.
Quantitative: Connected with the amount or number of something rather than with how good it is.
Yes. Several astronomers tested Kepler’s theory against astronomical observation. In the case of the
transit of Mercury in 1631, Kepler had been very uncertain of the parameters for Mercury, and
advised observers to look for the transit the day before and after the predicted date. Pierre
Gassendi observed the transit on the predicted date, a confirmation of Kepler’s theory. This was
the first observation of a transit of Mercury. However, his attempt to observe the transit of Venus
just one month later, was unsuccessful. Gassendi did not realise that it was not visible from most
of Europe, including Paris. Jeremiah Horrocks, who observed the 1639 Venus transit, used his own
observations to adjust the parameters of the Keplerian model. He predicted the transit and then built
apparatus to observe the transit. He remained a firm advocate of the Keplerian model.
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Activity 8: Research Newton’s Law of Universal Gravitation
LB page 239
Answer
When you are standing on Earth, it may seem like the distance between you and Earth is zero. But the
distance is measured between the centres of the two objects and not the edges. So, the distance between
you and Earth is actually the distance from the centre of the Earth to your belly button.
As the distance between two objects gets larger, the gravitational force between them gets smaller. It
never reaches zero; it just gets too small to matter. If you were suddenly suspended in space twice as far
from the centre of the Earth as you are now, the gravitational force would be one fourth as much as it is
on Earth’s surface. If you weigh 100 kg, you would suddenly weigh 25 kg. No matter how far you go from
Earth, there would still be some very small gravitational force between you and the home planet.
Newton was able to formulate a simple equation to describe this: force is equal to Newton’s
gravitational constant, multiplied by the masses of the objects, then divided by the square of the distance
between the objects:
M1 M2
F=G}
r2
We are therefore able to walk and jump on Earth because the gravitational force between us and earth
is small enough to allow for this, but strong enough to prevent us from floating out to space.
Support for this unit
If it is not possible to take the learners to an observatory, or access the Internet, try to acquire educational
DVDs on the history of astronomy.
Topic 16: Historical development of astronomy
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TOPIC 16 REVISION
LB page 240
Science language activity
Answers
1.
2.
3.
System used by astronomers to describe the brightness of objects
The scientific study of the universe and celestial bodies, especially their positions and movements.
Ancient people noticed that the celestial objects (Sun, Moon, stars) each moved in similar patterns
over particular timeframes.
4. The stars all appear to move together across the sky during the night as if they are attached to the
inside of a vast dome.
5. This is the path that the sun appears to travel across the sky over the course of the year.
6. The forces that attract objects to the surface of Earth are the same everywhere in the universe.
7. A gravitationally curved path of an object around a point in space.
8. An astronomical model where Earth and planets revolve around the Sun as the centre of the universe.
9. An astronomical model where the Sun and planets move around Earth, which is the centre of the
universe.
10. The practice of observing celestial objects by using telescopes and other astronomical apparatus.
Test yourself
Answers
114
1.
Early people observed these patterns and used them to measure time and develop different calendars
for the three time periods:
a) Years: The time period of a year includes the four seasons and it is commonly based on the solar
year, which is the orbital period of Earth moving around the Sun. For early observers on Earth,
this corresponded to the period it takes the Sun to complete one course through the zodiac along
the ecliptic. There are other years in use, such as the lunar year of about 354.37 days. It consists
of twelve full cycles of the phases of the Moon. A seasonal year is the time between successive
recurrences of a seasonal event, such as the flooding of a river or the migration of a species of
bird.
(5)
b) Months: A month is a time period used with calendars. It was first used in Mesopotamia as a
natural period based on the lunar cycle. Early people, such as the San, measured the lunar cycle
according to how much of the moon was visible. These months of early times that were based on
the Moon’s orbital period last approximately 29.53 days. They are still the basis of many calendars today. Tally sticks such as the Lebombo bone found in Swaziland show that people have
counted days in relation to the Moon’s phases since prehistoric times.
(5)
c) Days: Since ancient times, the word ‘day’ has been used for several different spans of time based
on the rotation of Earth on its axis. Early people measured the day as the period from one sunrise or sunset to the next. The exact moment of, and the interval between, two sunrises or two
sunsets depends on the geographical position (longitude as well as latitude), and the time of year.
This is the time as indicated by ancient sundials.
(5)
2.
The learners can mention any of the relevant stories and interpretations from the Learner’s Book to
illustrate their answer, or any others they may have heard of. People used these patterns in different
ways, such as to denote a time for planting, finding direction and to mark special holy days:
a) Agriculture: The Basutho people called the Belt stars of Orion the ‘Three Pigs’. In South Africa,
they were called the ‘hoeing stars’. Their last visible rising after sunset has been celebrated as a
sign to begin planting. The Bantu tribe called the group ‘the ploughing constellation’, because its
rising in the early morning in mid-winter told them to go out in the cold and plough. In Swahili,
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b)
c)
3.
a)
b)
c)
d)
e)
they are called Kilimia, which means ‘to dig or cultivate’. They were a sign that rain was near.
The Seven Sisters (Pleiades) is known as Seleme se setshehadi in Sesotho, meaning ‘the female
planter’. Its disappearance in April (the tenth month) and the appearance of the star Achernar,
signals the beginning of the cold season. Pleiades was named Khuseti or Khunuseh by the Khoikhoi, which translates as ‘rain stars’.
(5)
Finding direction: The old idea of the celestial sphere remains useful because it provides a simple
way of observing the stars from Earth. For thousands of years, the reference points on the celestial sphere have been used as maps for direction. Early people learned that they could tell direction just by the positions of certain stars. The Bushmen believed that the Milky Way was composed of wood ashes thrown up into the sky by a girl, so that people might see their way home at
night.
(5)
Marking special holy days: It is generally believed that the first astronomers were religious leaders. Ancient structures with astronomical alignments, such as Stonehenge and Nabta Playa in
the Sahara desert, probably fulfilled both astronomical and religious functions. These ancient
stone formations were built for the purpose of measuring time by tracking the movements of the
Sun. Muslims have for centuries used the lunar calendar to celebrate Eid and to mark the start
of the fasting month of Ramadan. Bushman healers and shamans greet the bright Evening Star,
the planet Venus, with a special dance. When isiLimela (Seven Sisters) is renewed, the year is
renewed. Xhosa men counted their years of manhood from the time in June when isiLimela first
became visible.
(5)
Nicolaus Copernicus suggested that the Sun was the centre of the Solar System (1514).
Galileo Galilei made the first telescope to observe planets and their moons (1610).
Johannes Kepler used mathematics to describe orbits accurately (1609).
Isaac Newton showed that gravity held the Solar System together (1687).
Robert Innes discovered the four closest stars, other than the Sun, to Earth in 1915 in
South Africa.
(2)
(2)
(2)
(2)
(2)
Total: 40
Topic 16 revision
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MEMORANDA FOR PRACTICE EXAMS
PRACTICE EXAM: TERMS 1 AND 2
1.
2.
3.
a)
b)
c)
B
A
C
(3)
a)
b)
c)
d)
e)
Decomposers
Ecosystem
Adaptation
Zygote
Molluscs
(5)
a)
b)
c)
1: sperm duct or vas deferens; 2: urethra; 3: penis
(3)
They produce sperm cells and the male hormone testosterone.
(2)
The testis are held close to the body, and so their temperature increases to body temperature,
which is not good for sperm production.
(2)
One sperm cell
(1)
Both eggs could be fertilised and the woman could be pregnant with twins.
(1)
Pollen that sticks to the stigma grows a pollen tube down the style towards the ovary. It contains
the male cells. When the tube reaches the ovule or egg cell, the tube opens to release the male
cells.
(3)
d)
e)
f)
4
a)
b)
c)
d)
116
i) Colourless
(1)
ii) Red
(1)
iii Yellow
(1)
i) Colourless
(1)
ii) Purple
(1)
iii) Yellow
(1)
Red
(1)
Phenolphthalein, because it is pale pink in pH 9–10, red in pH above 11, and colourless in pH
less than 8.
(2)
5.
a)
b)
Chromatography
(1)
Ink is generally made up of a number of different pigments. Ink will dissolve in methylated
spirits. More soluble pigments will travel faster through the paper and cover a longer distance.
Less soluble pigments will travel slower and only cover a short distance. In this way, we can
identify the colours of the different pigments that were used to make the ink.
(3)
6.
Add water to dissolve the salt. Filter the mixture and collect the salt water in a beaker. Collect the salt
by evaporation. Sieve the rice and pepper mixture using a sieve that has holes that are too small for
the rice to pass through.
(3)
7.
a)
Cat: vertebrate, mammal
Spider: invertebrate, arachnid
Hake: vertebrate, fish
Dove: vertebrate, bird
Locust: invertebrate, insect
Frog: vertebrate, amphibian
Cow: invertebrate, mammal
(7)
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b)
8.
9.
Monocotyledonous plants
Dicotyledonous plants
Parts of the flower are arranged in multiples
of three
Parts of the flower are arranged in multiples of four
or five
Strap-shaped leaves with parallel venation
Leaves have a variety of shapes with net venation
Fibrous root system
Taproot system
Usually small, soft green plants
Can be woody and grow very tall
(Any two differences)
c) Check if the plant has cones with naked seeds.
(2)
(1)
The metal part felt cold because metal is a good conductor of heat, so it conducts the heat away
quickly which leaves Rashid’s lips feeling cold. Wood is a poor conductor and does not carry the
heat away, so it feels warm.
(2)
a)
b)
c)
d)
10. a)
b)
c)
The different metals
(1)
The time taken for the Vaseline to melt
(1)
Keep all variables the same, for example the length and diameter of the metals and the time that
the metal was held in the flame.
(2)
He could use the Vaseline to stick some thumbtacks to the pieces of metal and then time how
long it takes for each to drop off. This is a more accurate way of determining how good the
metal is at conducting heat.
(2)
Metals are shiny and attractive and can be used to make jewellery. They are good conductors of
heat and electricity, and can be used to carry electricity to people’s homes. They are malleable
so they can be bent into different shapes and made into things like pots, arrow heads and knives
without breaking. (Any two)
(2)
Magnesium: Mg; Copper: Cu
(2)
Substances that have some properties of metals and some properties of non-metals. They are
found between the metals and the non-metals on the Periodic Table.
(2)
Total: 60
PRACTICE EXAM: TERMS 3 AND 4
1.
2.
a)
b)
c)
d)
e)
f)
D
C
A
D
C
B
(6)
a)
b)
c)
d)
e)
f)
Joule
Koeberg Nuclear Power Station
Insulator
Constellation
Spring high tide
Moon
(6)
Practice examination: Term 1 and 2
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3.
a)
b)
c)
d)
4.
a)
b)
c)
d)
e)
f)
5.
Energy stored in your muscles
hands move against each other
hands are
warmed up
(3)
100 J – 75 J = 25 J
(2)
Birds ruffle their feathers to trap air between them. Air is an insulator or a poor conductor
and so heat loss from the body is reduced.
(2)
When an air conditioner is placed high on a wall, the cold air from it sinks and flows to the
ground. As the air warms up, it starts to rise, creating a convection current. In this way, the cool
air is circulated around the room.
(3)
Length and diameter of the rods, distance from flame, size of drawing pin, amount of
Vaseline used to attach the drawing pin (Any two)
Time taken for the drawing pin to drop
Stopwatch or watch with a second hand
Type of material
The material that is the poorer conductor will take longer for the heat to travel through it
and melt the Vaseline. Therefore, the last pin to drop is held with Vaseline on the material
that is the poorer conductor.
Copper is a good conductor, so it is used to make cooking pots. Plastic is a poor conductor,
so it is used to make pot handles. (Any similar, reasonable answer)
(2)
(1)
(1)
(2)
(3)
(2)
a)
40
35%
30
25%
25
20
15
10%
5
5%
5%
Running the
refrigerator
10
Running TV, laptops
and computers
Amount of energy used (%)
35
10%
5%
Running the
washing machine
Other
Cooking food
Heating water
Heating the house
0
Energy usage of an urban family
b)
c)
6.
118
a)
(5)
They should insulate their home by doing the following: place insulation in the ceiling, install
glazed windows with trapped air (double glazing), seal doors and windows to prevent heat
escaping (any one idea with the explanation of how it prevents heat from escaping)
(3)
Walls were built from stone, mud or grass, which are insulators; roofs were built from grass or
thatch which are insulators; thick walls that further insulate homes were painted white on the
outside to reflect sunlight (any two)
(2)
The Sun provides energy for plants to make food, and it provides warmth for plants and animals
to live. It also drives the water cycle. (Any two reasonable answers)
(2)
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b)
c)
d)
• Plants absorb energy from the Sun from photosynthesis.
• Dead plants deposited in swamps are covered by sand and mud.
• Layers of sand and mud change the plants into coal.
• The coal stores the energy from the Sun that was in the plants.
• People use the stored energy when they burn coal.
(5)
Oil or gas
(1)
They are non-renewable. They produce environmental pollution when burnt. They release carbon
dioxide, which leads to global warming. They can cause the acidity of rain to increase, which can
cause plants and animals to die.
(1)
oblique rays
Earth’s axis
equal amounts
of solar energy
direct rays
7.
8.
(4)
equator
a)
b)
The force of gravity depends on how much mass the two objects have and how far apart the centres of the two objects are.
(2)
To prevent themselves from drying out when they have no water covering them.
(2)
Total: 60
Practice examination: Term 1 and 2
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TEST AND EXAM SECTION
TERM 1 TEST
1.
2.
Multiple choice:
Choose the correct answer and write down the number and the letter of your choice.
a) The largest biological system on Earth is a/an …
A ecosystem
B biosphere
C habitat
D environment
b) The dependent variable is the variable that …
A is changed
B is kept the same
C is measured
D is controlled
c) Plants that produce cones and have naked seeds are called …
A angiosperms
B gymnosperms
C monocotyledons
D dicotyledons
d) Arthropods are animals that have …
A an exoskeleton
B an exoskeleton and six jointed legs
C six jointed legs and two pairs of wings
D an exoskeleton and jointed legs
e) Respiration is the process during which …
A oxygen is used to make food
B carbon dioxide is used to release energy
C oxygen is used to break down food
D carbon dioxide is used to make food
(5)
Analyse the graph below, which shows the height ranges in a Grade 7 class.
Number of learners
20
15
10
5
0
120–124 125–129 130–134 135–139 140–144
Height range (cm)
a)
b)
c)
d)
120
Name the independent variable.
Describe how this investigation would be done so that it is fair.
Identify how many learners had a height range of 125–129 cm.
Identify the most common height.
(1)
(1)
(1)
(1)
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3.
Look at the diagram of the flower below:
a)
b)
c)
4.
Provide labels for the parts 1, 3 and 7.
Describe the function of the part labelled 2.
State whether this flower is bisexual or unisexual.
(3)
(2)
(1)
Look at the photographs of the invertebrates shown below.
a) Give three features that A and C both have that you can see in the photographs.
b) To which class do A and C belong?
c) Describe one way in which B is adapted to life on land.
(3)
(1)
(2)
5.
Tabulate two differences between monocotyledonous and dicotyledonous plants.
(2)
6.
Look at the diagram below of the male reproductive system:
Term 1 test
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a)
b)
c)
d)
Provide labels for the parts 1, 7 and 9.
Give the number of the structure responsible for making sperm.
Give the number of the structure responsible for carrying semen.
Condoms are contraceptives. Discuss two advantages of using a condom as a contraceptive.
(3)
(1)
(1)
(2)
Total: 30
TERM 1 TEST MEMORANDUM
1.
a)
b)
c)
d)
e)
B
C
B
D
C
(5)
2.
a)
b)
c)
d)
Height range
Keep all variables the same and change one only.
Six learners
130–134 cm
(1)
(1)
(1)
(1)
3.
a)
b)
1: stigma; 3: ovary; 7: anther
(3)
The style holds the stigma in a position in which it will come into contact with animals or insects
so that pollination can occur.
(2)
Bisexual
(1)
c)
4.
a)
b)
c)
Eight legs, two body regions, exoskeleton
(3)
Arachnids
(1)
A waxy cuticle reduces loss of moisture, wings for flying to find more food or escape enemies,
green or brown so they are camouflaged from enemies (any one)
(2)
5.
Any two of the following points:
Monocotyledons
Dicotyledons
Strap-like leaves with parallel veins
Leaves have different shapes and net veins
Adventitious root system
Taproot system
Soft, green stem
Stems may be green, or hard and woody
Leaves attached to stem by a sheath
Leaves attached to the stem by a petiole
Parts of the flower in multiples of three
Parts of the flower are in multiples of four or five
(2)
6.
a)
b)
c)
d)
1: sperm duct/vas deferens; 7: penis; 9: testis.
9
1
They are cheap and easy to obtain, they are effective and they prevent the transmission of
sexually transmitted diseases. (Any two)
(3)
(2)
(2)
Total: 30
122
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TERM 2 TEST
1.
Match the statements from Column B with the items in Column A. Write only the letter next to the
question number.
Column A
Column B
a) Condensation
A. Good conductors of electricity and heat
b) Metals
B. Elements on the far right of the Periodic Table
c) Filtration
C. A method where a filter is used to separate a liquid from a solid
d) Non-metals
D. The change of state from a gas to a liquid
(4)
Study the bar graph below and answer the following questions.
80
78%
Percentage of used materials
that are recycled (%)
70
60
50%
50
40
30
17%
20
plastic
0
glass
10
metals
2.
Recycled materials
a)
b)
c)
d)
3.
Explain what the term ‘recycled’ means.
(1)
Which material does the graph show to be recycled the most?
(1)
Give an example of one other material that is not on the graph that can also be recycled.
(1)
Discuss the impact that waste can have on the environment if these materials are not recycled. (1)
Complete the table by categorising each substance as an acid, base or neutral, and stating the colour
of each substance in universal indicator and blue litmus.
Substance
Acid, base or neutral
Sulfuric acid
Acid
Pure water
Colour in universal indicator Colour in blue litmus
Green
Salt water
Soap
Blue
Blue
Purple
(7)
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4.
Select from the list below the substance that best fits the description given. You may use a word once,
more than once or not at all. Use a Periodic Table to help you.
iron
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
5.
vinegar
copper
plastic
lithium
hydrogen
silicon
A semimetal that can conduct electricity
A substance used to cover the handle of a cooking pot
An unreactive metal commonly used in electrical wires
A non-metal that is a gas at room temperature
An element that is in the same group as sodium
An element that is in the same period as helium
A substance that has a pH below 7
A material that is magnetic
A mixture
A substance that tastes sour
air
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
The table below shows how the temperature of water increases with time as it is heated with a Bunsen
burner.
Time (s)
Temperature of water (°C)
0
20
10
40
20
60
30
80
a)
b)
c)
Use the data in the table to draw a line graph showing the temperature of the water over time. (2)
Describe what would happen to the water when it reaches 100 °C.
(1)
Sea water contains salt. Explain how you would use your answer in 5(b) to separate the salt
from the water.
(2)
Total: 30
TERM 2 TEST MEMORANDUM
1.
2.
a)
b)
c)
d)
D
A
C
B
a)
The word ‘recycled’ is used to describe waste materials that have been broken down into different
parts and reused to make new products.
(1)
Metals
(1)
Paper
(1)
Waste materials that are not recycled end up in landfill sites. Not all the waste decays, and some
of it seeps into the soil, which contaminates groundwater supplies. Suitable areas for landfill sites
are quickly running out.
(1)
b)
c)
d)
124
(4)
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3.
4.
Substance
Acid, base or neutral
Colour in universal indicator
Colour in blue litmus
Sulfuric acid
Acid
Red
Red
Pure water
Neutral
Green
Blue
Salt water
Neutral
Green
Blue
Soap
Base
Purple
Blue
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
(7)
Silicon
Plastic
Copper
Hydrogen
Lithium
Hydrogen
Vinegar
Iron
Air
Vinegar
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
5. a) Make sure that the line graph has the following components:
•
x-axis label: Time (s)
•
Appropriate scale and neatly plotted data
•
y-axis label: Temperature of water (°C)
•
A heading: Graph to show that the temperature of water increases with time as it is heated
with a Bunsen burner.
(2)
b) The water would start to boil and then evaporate.
(1)
c) Evaporation can be used to recover the salt particles from sea water. The solution is heated to
increase the rate of evaporation. After the liquid has evaporated, the solute particles will be
left behind.
(2)
Total: 30
Term 2 test memorandum
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TERM 3 TEST
1.
Multiple choice:
Choose the correct answer and write down the number and the letter of your choice.
a) How does heat mainly travel through air?
A Conduction
B Convection
C Radiation
D Evaporation
b) Busisiwe placed her hands around the following containers filled with hot water. She was careful
not to touch theAcontainers. Her results will show that ...
A
c)
d)
e)
126
B
A container A felt the hottest
B container B felt hottest
C container A felt coolest
D containers A and B were the same temperature
What conclusion did Busisiwe reach for the above experiment?
A Shiny surfaces absorb heat best
B Dark surfaces reflect heat best
B
C Black surfaces transmit heat best
D Black surfaces radiate heat best
Which of the following statements is true about solids that allow heat to pass through them?
A They are also called insulators
B They are also called heaters
C Most metals are good conductors of heat
D Mostly made of plastic
Which of the following list is a combination of insulators?
A Aluminium, tin and wood
B Lead, glass and copper
C Iron, air and plastic
D Cork, plastic and air
(5)
2.
State the principle of conservation of energy.
(3)
3.
Why is a thick layer of blanket most likely to be warmer than a thin layer of sheeting?
(3)
4.
Explain why polar bears who live in very cold regions have a large amount of fur covering their bodies.
(2)
5.
If your parents decide to have an air conditioner installed in your house, where should you place it?
Explain your answer.
(3)
6.
Your Grade 7 class did an outdoor experiment to determine how long it takes to burn a piece of
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white paper by concentrating the Sun’s rays with a magnifying glass. The class was divided into 6
groups. The groups started directing the sun at the magnifying glass at the same time. They recorded
the time taken to for a piece of paper to ignite. The results were as follows:
•
Group 1’s paper ignited after one minute.
•
Group 2’s paper ignited after three minutes.
•
Group 3’s paper ignited after six minutes.
•
Group 4’s paper ignited after eight minutes.
•
Group 5’s paper ignited after seven minutes.
•
Group 6’s paper ignited after ten minutes.
a) Arrange the results in a table. Make sure that every column and row has a heading.
(4)
b) Use the information to plot a bar graph. Give labels for the y- and x-axes. Supply the graph
with a heading. Use a sharp pencil and ruler. Do not shade the bars. Make your graph neat
and accurate.
(7)
c) Which group’s paper took the longest time to burn?
(1)
d) Give two possible reasons why the group you chose in the previous question took so long to burn
their paper.
(2)
Total: 30
TERM 3 TEST MEMORANDUM
1.
a)
b)
c)
d)
e)
C
A
D
C
D
(5)
2.
Energy cannot be created or destroyed. It can only be transferred from one form to another.
3.
The blanket is an insulator. There are holes between the fibres of the blanket that trap air. Air is a
poor conductor, so blankets help us to retain heat, keeping us warm.
(3)
4.
The fur is an insulator. It prevents their bodies from losing heat to the surroundings. (You can also
award marks for saying fur traps air. Air is an insulator.)
(2)
5.
The air conditioner must be installed high up, near the ceiling. Cold air sinks; cool air will circulate
through convection.
(3)
6.
(3)
a)
Table showing the time required to burn newspaper by concentrating the Sun’s rays
Group number
Time (minutes)
1
1
2
3
3
6
4
8
5
7
6
10
(4)
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b)
c)
d)
Make sure that the bar graph has the following components:
•
x-axis label: Time (s)
•
Appropriate scale and neatly plotted data
•
y-axis label: Group
•
A heading: Graph to show the time required to burn newspaper by concentrating
the Sun’s rays
(7)
Group 6
(1)
They may have started after the others. They may have had more white on their newspaper.
They may be in an area that has more shade. They may not know how to focus the sunlight to
burn the paper. (Any two answers or any other reasonable answer)
(2)
Total: 30
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MID-YEAR EXAMINATION
1.
Multiple choice:
Choose the correct answer and write down the number and the letter of your choice.
a)
b)
c)
d)
e)
f)
2.
3.
The best method to separate a mixture of sand and iron nails is …
A filtration
B magnetism
C evaporation
D sieving
Litmus paper was used to test if vinegar was an acid, a base or neutral. Which of the following
results would be true for vinegar?
A Red litmus paper remains red, blue litmus paper remains blue
B Red litmus paper turns blue, blue litmus paper remains blue
C Red litmus paper remains red, blue litmus paper turns red
D Red litmus paper turns red
The symbol for sodium is …
A S
B Si
C Na
D N
Which of the following cannot be recycled?
A Glass, paper, tin
B Fruit juice bottles lined with plastic, potato bags
C Cans, bottles, office paper, cardboard
D Metal, glass, plastic, vegetable peels
A pollen grain has two sacs filled with air. It is probably carried by …
A birds
B wind
C insects
D water
During respiration …
A food is produced
B energy is needed
C growth occurs
D energy is released
(6)
Give the correct scientific term for each of the following:
a) The largest group into which organisms are placed
b) The plants that bear their seeds in cones
c) The method used to separate different colours of a dye
d) Starchy food stored in a seed
e) A stage in the human life cycle when sex organs mature
(5)
Nomsa and Tembela tested the strength of paper. They cuts strips of paper and joined the two ends
together with sticky tape. They then hung the paper on a hook attached to a spring. They pulled the
other end of the paper until it began to tear. They measured the length that the spring was stretched
before the paper tore.
They wanted to know if wide strips would be stronger than narrow strips of paper.
a)
b)
Write a hypothesis for this investigation.
Identify the factors or variables that they would need to keep constant in their test.
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(2)
(2)
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c)
d)
e)
Name the factor that they would change.
(1)
Describe how they would ensure that the test is fair.
(2)
Nazlie then decided to compare the strength of different kinds of paper. She tested the paper
three times. She also dribbled five drops of water onto each paper and performed the test three
times again. Each time, she measured the length of the spring in centimetres before the paper
broke. Look at the table of results below:
Length of spring
attached to dry
newspaper (cm)
Length of spring
attached to wet
newspaper (cm)
Length of spring
attached to dry
magazine paper (cm)
Length of spring
attached to wet
magazine paper (cm)
Test 1
2,1
0,6
4,5
3,2
Test 2
2,1
0,5
5
2,5
Test 3
2,5
0,4
4
2,5
i)
ii)
4.
a)
b)
c)
5.
a)
b)
c)
Explain why Nazlie tested each paper three times.
(1)
Look carefully at the table of results. What two facts can you learn about the strength of wet
and dry magazine paper and wet and dry newspaper?
(2)
Define the term ‘adaptation’.
Discuss how gemsbok are adapted to live in desert ecosystems, and how they are adapted to
protect themselves from enemies.
Describe one behaviour that the gemsbok has that will help it to survive hot, daytime
temperatures.
State two characteristics of an alkali.
Red and blue litmus paper is an indicator. Explain what an indicator is.
Emma made her own indicator using black tea. She added the black tea to three different
substances. Her results are shown below:
Beaker A
Beaker B
Beaker C
Vinegar
Water
Soapy water
i) What do you call the black tea?
ii) Predict the colour change you would see if you added the black tea to some bleach.
iii) Predict the colour of the tea in an acid.
6.
a)
b)
c)
130
(2)
(3)
(1)
(2)
(2)
(1)
(1)
(1)
Define the terms: ‘element’ and ‘semimetal’.
(2)
Give the symbol for each of the following:
i) Lithium
(1)
ii) Sulfur
(1)
Copper is often used to make pipes to carry water in a home. Describe two properties of copper
that make it suitable for this purpose.
(2)
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7.
Look at the diagram below.
11
22
33
44
a)
b)
c)
8.
Provide labels for the parts 1, 2, 3, and 4.
Suggest how the structure of parts 1 and 3 helps them to carry out their functions.
This diagram shows a flower with large petals that produces lots of nectar. Suggest how the
flower is pollinated.
d) Describe what happens to a human egg after it is fertilised.
You have a mixture of alcohol and water.
a) Name the method that you would use to separate this mixture.
b) Explain why the method would be suitable.
c) Explain how the mixture is separated.
(4)
(4)
(2)
(4)
(1)
(1)
(4)
Total: 60
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MID-YEAR EXAMINATION MEMORANDUM
1.
a)
b)
c)
d)
e)
f)
B
C
C
B
D
D
(6)
a)
b)
c)
d)
e)
Kingdom
Gymnosperms
Chromatography
Endosperm
Puberty
(5)
3.
a)
b)
c)
d)
e)
A wide strip will pull the spring further before breaking.
The type of paper used, the length of paper used
The width of the paper
All factors must be kept the same except the one that is changed.
i) To ensure that the results were accurate
ii) Dry paper is stronger than wet paper and magazine paper is stronger than newspaper.
(2)
(2)
(1)
(2)
(1)
(2)
4.
a)
b)
An adaptation is a characteristic that helps a living thing survive in its environment.
Blood is cooled in the gemsbok's nose before it enters the brain; long, sharp horns are used
to drive predators away.
It moves into the shade in hottest part of the day.
(2)
(3)
(1)
2.
c)
5.
a)
b)
c)
They are slippery to the touch, turn red litmus blue
Substance that changes colour in the presence of an acid or alkali
i) Indicator
ii) It would turn dark brown
iii) Lighter colour than normal tea.
(2)
(2)
(1)
(1)
(1)
6.
a)
Element – pure substance that cannot be broken down further; semimetal – substance with
some properties of metals and some properties of non-metals
i) Li
ii) S
Malleable, good conductor of heat, hard or solid (any two)
(2)
(1)
(1)
(2)
b)
c)
7.
a)
b)
c)
d)
132
1: stigma
2: petal
3: stamen
4: ovary
(4)
The stigma receives the pollen. It has a large surface area to collect pollen.
(4)
The stamen produces pollen. It sticks out of the flower so that the pollen is exposed to
pollinating agents such as wind, insects or birds.
The large (possibly brightly coloured) petals and abundant nectar will attract insects and birds.
The flower will either be insect- or bird-pollinated.
(2)
The egg is fertilised and moves in to the uterus. The uterus has a thick blood layer and the
fertilised egg sinks into it. This is called implantation. The woman is now pregnant.
(4)
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8.
a)
b)
c)
Distillation
Different boiling points
The mixture is heated to 70 °C and the alcohol evaporates. The vapour is cooled in the
condenser and it condenses. The alcohol is collected. The temperature must not be allowed
to go over 70 °C.
(1)
(1)
(4)
Total: 60
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END-OF-YEAR EXAMINATION
1.
Multiple choice:
Choose the correct answer and write down the number and the letter of your choice.
a)
Which of the following options below represents a form of non-renewable energy?
A Hydropower
B Wind power
C Biofuel
D Uranium
Which one of the following represents the correct unit of energy?
A Meter
B Joule
C Second
D Kilogram
Which one of the following materials is classified as an insulator?
A Wood
B Copper
C Steel
D Nichrome
Which of the following parts in a coal-fired power station converts mechanical energy into
electrical energy?
A Boiler
B Cooling tower
C Generator
D Turbine
The tilt of Earth’s axis …
A changes as Earth orbits around the Sun
B does not change as Earth orbits the Sun
C is reversed from summer to winter
D alternates as Earth revolves in a clockwise direction
The tendency of all objects to attract each other is called …
A its mass
B an attractive force
C gravity
D its rotation
The first person to propose that the planets revolved around the sun was …
A Galileo Galilei
B Aristotle
C Albert Einstein
D Nicolaus Copernicus
(7)
Give the correct term for each of the following. Write the number and your answer.
a) The ability of a system to do work
b) The non-renewable energy source used to make paraffin, diesel and petrol
c) The energy an object has due to movement
d) The energy that an object has because of the movement of particles that make up the object
e) A fan-like machine that turns to produce mechanical energy
f) The line dividing the lit half of Earth from the dark half
g) The predictable, repeated rise and fall of sea and ocean levels
h) Communities of living organisms and their interactions with the environment
i) The path that the Sun appears to travel across the sky over the course of a year
(9)
b)
c)
d)
e)
f)
g)
2.
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3.
a)
b)
c)
d)
e)
4.
6.
7.
(1)
(2)
(1)
(1)
(2)
Look at the diagram below and answer the following questions.
a)
b)
5.
Coal is an example of a non-renewable source of energy. Name the main use of coal in
South Africa.
Explain what is meant by a renewable source of energy.
State one other example of a renewable source of energy.
Name the most common use of solar energy in South Africa.
Hydropower and wave and tidal power are not suitable for use in South Africa. Explain
why this statement is true.
Name the type of energy system shown in the diagram.
Draw an energy flow diagram for the system.
(1)
(2)
Look at the picture of a cell below.
a) Name the type of energy that is stored in the cell.
b) Explain the law of conservation of energy. Use the example of the cell in your answer.
Dumi decided to build a device that will use an electric motor to move a bucket of water up and
down a ramp. Jill says that some energy will be wasted.
a) Explain what Jill meant when she said that energy would be ‘wasted’.
b) Dumi decides to build an energy-efficient system. What is meant by an energy-efficient system?
South Africa has very little spare capacity to supply electrical energy. At times the demand for
electricity exceeds supply.
a) Name the system that generates and supplies electricity throughout South Africa.
b) What is the main energy source of power in South Africa?
c) List two ways in which you can reduce the amount of electricity you use.
d) Explain why the supply of energy to our homes is not 100% efficient.
End-of-year examination
9780636140905_plt_nat_g07_tg_eng_za.indb 135
(1)
(2)
(2)
(2)
(1)
(1)
(2)
(2)
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8.
Mr Abba designed a pot-in-pot cooling system for people in rural areas where there is no
electricity. He placed a small clay pot inside a larger one. The space between the two pots was filled
with moist soil. The inner pot is filled with food and covered with a wet cloth. As the water in the
sand evaporates, it carries heat away with it.
a) Name the method of heat transfer between the sand and the clay.
(1)
b) Explain why the pots are made of clay.
(2)
c) Vusi investigated how using different materials in place of the soil would help to keep the food
cool. Name the independent and the dependent variables and state how the dependent variable
would be measured.
(3)
9.
a)
b)
10 a)
b)
c)
d)
11 a)
b)
How would our lives be different if:
i) Earth was much closer to the Sun?
ii) Earth turned more slowly on its axis?
iii) Earth’s axis was not tilted at all?
Name the process during which plants use energy from the Sun to make food.
(2)
(2)
(1)
(1)
Name the phase of the Moon shown below.
(1)
How long will it take until this phase will be visible again?
(1)
Name two factors that affect the gravitational pull which the Moon would exert on an object. (2)
Name the type of tide experienced when the Moon shown above is in line with Earth and
the Sun.
(1)
Explain what is meant by the ‘heliocentric model’.
List two ways in which early people made use of predictable patterns that they observed
in the sky.
(2)
(2)
Total: 60
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END-OF-YEAR EXAMINATION MEMORANDUM
1.
a)
b)
c)
d)
e)
f)
g)
D
B
A
C
B
C
D
(7)
a)
b)
c)
d)
e)
f)
g)
h)
i)
Energy
Oil
Kinetic
Heat
Turbine
Circle of illumination
Tides
Ecosystem
Ecliptic
(9)
a)
b)
c)
d)
e)
Electricity, petrol, other synthetic fuels (Any one)
A source of energy that can be replaced
Hydropower, soloar power, wave and tidal power, wind, biofuel (Any one)
To heat water
In South Africa, there are not many rivers that are large enough; tidal conditions are not
suitable and the waves are not strong enough
(2)
a)
b)
Mechanical
Potential energy
(1)
(2)
5.
a)
b)
Chemical potential energy
(1)
Energy cannot be created or destroyed, it can only be transferred into another type of energy.
In the cell, energy is in the form of chemical potential energy and it is transferred to another
type of energy, such as light or heat energy.
(2)
6.
a)
The machine will be able to move the bucket up and down the hill but it will also produce heat
and sound energy that will not be useful to Dumi and Jill.
(2)
A system which produces less wasted energy. A system where more input energy is converted
to useful energy.
(2)
2.
3.
4.
b)
7.
a)
b)
c)
d)
8.
a)
b)
c)
kinetic energy
(1)
(2)
(1)
(1)
National electricity grid
(1)
Coal
(1)
Energy-saving bulbs, switching off appliances when they are not in use, do not leave cellphone
chargers plugged in, do not turn on heaters or air conditioners, rather change your clothing
(any two)
(2)
Electricity is lost in the cables as it is transferred from power stations to homes. The cooling
towers of power stations also have a lot of water escaping as steam, which is a loss of energy. (2)
Conduction
Clay is an insulator that does not allow heat to move through it easily.
The independent variable is the different materials used in place of the soil. The dependent
variable is temperature, which would be measured with a thermometer.
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(1)
(2)
(3)
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9.
a)
There would be no life as we know it because it would be too hot for life to survive.
Day and night would be longer. On average, nights would be colder and days would
be hotter.
iii) We would not have seasons.
Photosynthesis
(2)
10. a)
b)
c)
d)
Full moon
29 days
The mass of the object and how far away it is from the Moon
Spring tide
(1)
(1)
(2)
(1)
11. a)
b)
The Sun is the centre of the Solar System and the planets orbit the Sun.
They used the patterns to determine when to plant and harvest crops; they also used the sky
to navigate.
(2)
b)
i)
ii)
(2)
(1)
(1)
(2)
Total: 60
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