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Stage
5
Dr Loo Yoke Leng
Dr Ivan Yow
Teachers and students have FREE access to the online textbook and workbook at
Teachers and students have free access to the online textbook and workbook at
www.AlstonDigital.sg
www.AlstonDigital.sg. Teachers will also have free access to the online teacher’s guide.
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How to register?
● Email enquiry@alstoneducation.com to request for a registration form.
Terms and conditions:
● Access is granted to teachers and students of schools who have adopted the series and registered
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with the publisher.
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from the first day of the school year. A free access can only be activated once.
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● Each purchase of a textbook or workbook is entitled to a 12-month free access respectively, starting
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Published by Alston Education Pte Ltd
627A Aljunied Road, #07-03 Biztech Centre, Singapore 389842
enquiry@alstoneducation.com
www.alstoneducation.com
© 2022 Alston Education Pte Ltd
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All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without the prior
permission of the copyright owner.
Version 2023.2
ISBN 978-981-4437-05-9
Publisher: Sim Wee Chee
www.AlstonDigital.sg
Name:
Class:
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How to use the book
Hi, I am Cyrus!
I love to experiment
and discover many
cool things about
Science!
on
P
te
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Every chapter begins with
an interesting problem
scenario to spark learners’
curiosity about the world
around them. Learners are
required to weave all their
learning together to solve
this problem by the end of
the chapter.
ti
Questions that guide learners
to think about the problem
scenario and teach them how
to make use of the concepts
learnt in the chapter to solve
the problem.
E
du
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The learning outcomes
covered are listed to offer
teachers and learners a clear
overview of the chapter.
ed for seed
itions need
out the cond
Aim: To find
20
23
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Wrap five cress
seeds with a dry
paper towel.
4
n.
germinatio
seeds
Place the wrapped
and
into a resealable bag
‘E’. This
seal it. Label this bag
p.
set-u
is the experimental
2
A
Instructions:
of
1 Soak a sheet
paper towel with
water. Wrap five
cress seeds with the
wet paper towel.
Hello, I am Tim.
I like to gather information
about Science and
observe the world around
me. This is exciting!
yr
Let’s invest
3
Experiments and activities
that precede formal content
teaching to allow learners to
actively explore key science
concepts in the chapter.
Learners are encouraged
to infer concepts in their
own ways to form their
conclusions.
igate!
ls
to
n
Let’s investigate!
5
seeds
Place the wrapped
and
into a resealable bag
‘C’.
bag
this
l
Labe
it.
seal
p.
This is the control set-u
Prepare three
bags of the
experimental
set-up.
3
6
Prepare three
bags of the
control set-up.
Hey, I am Ada!
I am always
curious about the
things around me.
I like to use my
gadgets to find
out more about
Science!
ronments.
in the following envi
Place Bags E and C
7
On a windowsill with
light and warmth
Inside a cupboard
that is dark and warm
8
s
Predict how many seed
will germinate in the
Environment
Inside a cupboard that
warm
is dark and
On a windowsill with
and warmth
light
is dark
In a refrigerator that
and cold
12
Bag
In a refrigerator that
is dark and cold
ictions.
bags. Explain your pred
Prediction
E
C
E
C
E
C
Chapter 1
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Other main features
II
Retrace our steps
Questions that prompt
learners to recall prior
knowledge to understand
a new concept.
How to use the book
Watch out!
Questions or statements that
highlight and clear common
misconceptions, so that
learners obtain a clearer
understanding of the topic.
Think-Pair-Share
Questions that allow learners to
collaborate and discuss with one
another. Learners can apply what they
have learnt and this facilitates a deeper
understanding of the concepts taught.
Colourful illustrations with
clear and easy-to-read
explanations that cover key
scientific concepts. This helps
to engage learners, allowing
them to grasp important
concepts easily.
How do plants disperse their
seeds?
How are plants adapted to
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By wind
Some plants depend on
the wind to disperse their
seeds.
Hello, I am Vera!
I like to explore new
places and learn about
the world around me.
Let's go!
rsal by wind
Adaptation for seed dispe
y
plants are light. They usuall
The fruits or seeds of these
wings or parachutes.
like
look
that
s
have shape
te
By water
Some plants depend on
their
moving water to disperse
seeds.
on
P
Crack the case
Solids, Liquids and Gases
ca
such as
ls
to
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Gases
_______________ _______________
_______________
packed
packed
__________ at
________ positions
Solid
______________
or slide past one
another
Hydrogen
Gases can be
compressed
Nitrogen
have
can
Occupy space
so
A
Movement of
particles
No fixed volume
No fixed shape
Meow, I am Coco.
Let's embark on a fun
and exciting journey
to learn Science!
so
Gases can take the
volume of a container
______________
and randomly in
all directions
20
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Arrangement of
particles
Gas
A visually-appealing
mind map where
learners can recall key
concepts and evaluate
their understanding of
the chapter.
e
Carbon dioxid
Oxyg
en
Properties
have
Crack the case
Water vapour
have
Particle model
Adaptations of Plants
du
Chapter 2
E
26
ti
By exploding or
splitting open
Some plants disperse their
seeds by splitting open
their fruits. Others do so by
exploding their fruits.
parent plant.
Liquid
rsal by animals
Adaptation for seed dispe
plants are
The fruits or seeds of these
in nutrients.
high
are
or
sweet and fleshy
feed on them.
These attract animals to
on their fruits so
Some plants have hooks
themselves to
that the fruits can attach
the animal’s fur easily.
rsal by
Adaptation for seed dispe
exploding or splitting open
,
grown
fully
are
seeds
When the
des or
the fruit dries out and explo
seeds
the
ring
scatte
open,
splits
away from the plant.
By animals
Some plants depend on
animals to help carry
the seeds away from the
Solid
disperse their seeds?
rsal by water
Adaptation for seed dispe
plants are usually round.
The fruits or seeds of these
easily. The fruits or seeds
It helps them roll into water
float on water.
can
they
that
so
can trap air
Gases can take the
shape of a container
Gas
Chapter 3
Tick (✓).
What should Cyrus do to get the shampoo into the bottle quickly?
the
Cyrus should wait and let the shampoo flow from the funnel into
bottle.
to flow
Cyrus should use a bigger funnel instead to allow more shampoo
into the bottle.
He can
Cyrus can remove the tape that seals the bottle and the funnel.
slightly lift the funnel up as he pours the shampoo into the bottle.
Squeak! I am Momo!
Do you know, Science can be
found everywhere, even in the
smallest places!
kbook
or
W
Science keywords
Consolidation worksheet
Solids, Liquids and Gases
A list of key scientific
vocabulary covered
throughout the book.
45
Solve this!
Follow-up questions
after every new
concept for learners
to check their
understanding and
build process skills.
Science in context
Learners can link and
apply their scientific
knowledge to realworld contexts.
Clues
Definitions of
challenging English
words to aid learners'
understanding.
W
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Liquid
k
kboo
or
Worksheet
Learners are directed to the
relevant worksheets in the
workbook, reinforcing their
understanding of concepts.
How to use the book
III
27
Contents
Chapter 1
Life Cycle of Flowering Plants
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How do we tell if a living thing is a plant?
What are the parts and functions of a flower?
What are the key stages in the life cycle of a flowering plant?
2
What happens during reproduction in flowering plants?
te
Chapter 2
P
Adaptations of Plants
How are plants adapted for pollination?
What is seed dispersal?
How do plants disperse their seeds?
ti
How are plants adapted to disperse their seeds?
on
What are adaptations?
20
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What other adaptations do plants living in different environmental
conditions have?
du
Chapter 3
Solids, Liquids and Gases
E
What are the gases around us?
What are the uses of different gases?
What are the properties of gases?
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How do we use the particle model to describe solids, liquids and gases?
How do we use the particle model to explain the properties
of solids, liquids and gases?
34
A
Chapter 4
Changing States of Water
Why is water special?
20
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What are the melting point and freezing point of water?
What happens to the volume of water when it freezes?
What happens when water is heated?
Where does water disappear to when it is left exposed to the air?
What happens when gases are cooled?
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Chapter 5
46
Solute and Solvent
What happens when a solid is added to a liquid?
What are the characteristics of a solution?
yr
Do all solids dissolve and do all liquids act as solvents?
What happens to the particles of a solid when it is added to a liquid?
op
How much solid can be dissolved in a liquid?
C
How can we separate the solute and the solvent in a solution?
66
Chapter 6
Forces
Why do objects fall to the ground when we drop them in the air?
What are the forces acting on an object at rest on a surface?
What force causes an object at rest to start moving?
What forces can cause a moving object to slow down?
What are the forces acting on an object in water?
IV
Contents
82
Chapter 7
Magnets
What are the differences between a magnet and a magnetic material?
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Can we tell if an object attracted to a magnet is a magnet or a magnetic material?
What happens to a magnetic material when it is near a magnet?
What can cause temporary magnets to lose their magnetic properties?
96
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Do all magnets have the same magnetic strength?
P
Chapter 8
Digestive System
How do animals digest their food?
on
How do the organs in our digestive system break down food?
What do we need to eat and how much do we need to eat to be healthy?
112
ca
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What happens to our health if our diet is poor?
Chapter 9
du
Adaptations of Animals
What are adaptations?
What adaptations do animals have to help them feed on food?
E
What adaptations do animals have to obtain the food they eat?
What adaptations do animals have to help them escape from danger?
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What adaptations do animals have to help them reproduce?
What adaptations do animals living in a hot and dry environment have?
What adaptations do animals living in a cold environment have?
What adaptations do animals living in water have?
128
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Chapter 10
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Sound
How is sound produced?
How does sound travel to our ears?
Can sound travel through solids and liquids?
How does our body help us make different sounds?
How do we describe sounds?
150
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Chapter 11
Earth and Satellites
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How does Earth orbit the Sun?
What causes the different seasons?
What are satellites?
What makes up Earth's atmosphere?
Where can we find water on Earth?
Are all types of water on Earth pure?
168
Chapter 12
Pollution
What is pollution?
What is land pollution?
What is water pollution?
What is air pollution?
How can pollution occur on a global and local scale?
182
Contents
V
Let's think and work like a scientist!
Models and diagrams
A diagram or physical model helps to show the important
features of an object. They also help to describe the
scientific phenomena or processes found in nature.
on
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This paper model is
a physical model that
represents a seed that
disperses by wind. The way
this paper model flies and
spins in the air is similar to
how the seed moves in the
wind in real life.
Disperses by
animals
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20
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Lives in a hot
and dry
environment
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Lives in a ____
and dry
environment
C
VI
The way this ball sticks to
my socks is similar to how
some fruits can attach to
animal’s fur and disperse
by animals.
A
Lives in water
We can
come up with
a classification
key based on
the differences
observed in
living things.
ey
te the k
Comple se:
e
using th
have
e plant
Does th t trap air?
a
parts th
have
e plant
Does th m?
te
fleshy s
have
e plant
Does th ?
rk
thick ba
ls
to
n
Classification key
E
du
ca
ti
Disperses by
wind
Think like a scientist
Lives in a warm
environment
Can we use this key
to find out what type
of environment a
given plant lives in?
I am modelling
what is going
on in your
mouth now!
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Control and experimental set-ups in a fair experiment
In both the experimental set-up
and the control set-up, the control
variables are kept the same.
te
A control set-up helps us confirm
that the effect observed in the
dependent variable is due to the
independent variable and not other
variables in the experiment.
ti
on
P
In an experimental set-up, the
independent variable is different
from the one in the control set-up.
This allows us to compare results.
Control set-up
E
The surrounding temperature
may not be warm enough for the
seeds to germinate quickly.
We can improve the experiment
by placing these bags on the
windowsill.
A
ls
to
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To find out if water is needed for seed
germination, the presence of water is the
independent variable. So, only the towel
in Bag E is wet while the towel in Bag C is
dry. Both bags are exposed to the same
temperature and use the same type of seeds.
This is how we ensure that it is a fair test.
du
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Experimental set-up
20
23
Presenting results
This point that lies
far away from the line
of best fit is called an
anomalous result.
Equipment
Syringe
C
First, we determine the general direction of the trend indicated
by most of the points on the graph. Next, we draw a straight line
that can fit most of the points most closely. This line is called
a line of best fit.
Measuring
cylinder
Beaker
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Drawing a line of
best fit
Our investigation may not be
perfect. Sometimes, there may
be errors in our results and not all
the points can lie on one straight
line. These points follow a general
trend and we can show this trend by
drawing a line of best fit.
Thermometer
Forcemeter
Magnet
Metre ruler Stopwatch
Work like a scientist
VII
CHAPTER 1
Life Cycle of Flowering
E
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My seeds have exploded!
The notepaper is also
damaged. What has happened
to my seeds? What should I do
to grow my seeds?
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to
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The next day, Ada takes her
seeds out
from her bag. New things are
coming
out of the seeds. Ada does no
t know
what has happened to the se
eds. The
notepaper is also damaged.
du
ca
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on
P
te
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The Science teacher gave
the students some seeds an
d
instructions on a piece of
notepaper. The instructions
described how the seeds co
uld
be grown. Ada kept the seed
s
and the notepaper in her ba
g.
Plants
stages
What are the
le of a
in the life cyc
nt?
flowering pla
✓ Identify the parts of a flower and describe their functions.
Which stage of th
e
flowering plant’s
life
cycle is the green
bean seed at?
What Will I Learn
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✓ State that not all plants produce flowers.
✓ Identify the stages in the life cycle of a flowering plant.
✓ Describe seed germination and the conditions required for
seeds to germinate.
✓ Describe what happens during reproduction in flowering plants.
2
Chapter 1
What do seeds
need to grow into
a young plant?
How do we tell if a living thing is a plant?
Retrace our steps
What are the
major parts of a
flowering plant?
What are their
functions?
1
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Do all plants have flowers?
Let’s investigate!
P
te
e
d understand that ther
an
ts
an
pl
y
tif
en
id
To
:
m
Ai
ants.
are different types of pl
ca
ti
on
Materials:
Plant identification key
Digital camera
du
What type of plant is this?
Do not produce flowers
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to
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Produce flowers
Have
many ...
long and
thin ...
Big and
round ...
20
23
A
Have only
five ...
Plants that do not live on land
E
Plants that live on land
Example of an identification key
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Instructions:
1 Go to a school garden or park near your school.
2 Go for a plant walk. Sketch or take photographs of things that you
have identified as plants.
3 Sort your sketches or photographs. Classify the plants identified as
flowering and non-flowering plants.
4 Identify the plants using the identification key provided.
Questions:
1 Which characteristics did you use to identify plants?
2 Were there more flowering or non-flowering plants around your school?
3 Look at the non-flowering plants identified. What are their similarities?
Life Cycle of Flowering Plants
3
In general, most plants have the following features:
Have leaves
Have roots
Have a stem
Plants are generally green because they have
green-coloured substances known as chlorophyll to help
them absorb light energy from the Sun to make food.
Retrace our steps
P
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Are trees
plants? How do
you tell?
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E
du
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Chlorophyll
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23
A
Some plants have flowers. They are classified as flowering plants. Flowers
help the plants to reproduce. Flowers of these plants bloom when the plants
mature or have grown to become adult plants. For many flowering plants, their
flowers only last for a period of time.
The flowers of a tomato plant will eventually become fruits.
4
Chapter 1
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P
Cherry blossom tree
Mango tree
on
Cherry blossom trees and mango trees are examples of flowering plants.
A
ls
to
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E
du
ca
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Some plants do not have flowers. Mosses, ferns and conifers are plants that do
not have flowers. We classify them as non-flowering plants. They reproduce in
other ways.
Moss
Fern
Conifer
Solve this!
20
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Mosses, ferns and conifers are examples of non-flowering plants.
W
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Look at these plants. Are they flowering or non-flowering plants?
k
kboo
or
Worksheet 1
Life Cycle of Flowering Plants
5
What are the parts and functions of a flower?
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Flowers make plants attractive and beautiful. Flowers are also important in the
reproduction process in flowering plants. Without flowers, many plants cannot
reproduce and will become extinct.
on
P
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A flower has various parts. Each part plays an important role in the
reproduction process.
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23
A
ls
to
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The filament holds the anther up.
E
The anther contains pollen sacs. The
pollen sacs have pollen grains.
ti
Stamen
The stamen refers to the male
reproductive organ of the flower.
It consists of the anther and the filament.
6
Cross-section of a flower
Petals are usually colourful and have a sweet smell. This
helps to attract insects and small animals to the flower.
As plants cannot move, they depend on insects and
small animals to help transfer the pollen grains from the
male part to the female part of the flower during the
reproduction process.
Chapter 1
Caution!
Only use equipment given
Do not run around with equipment
Take care of your hands when
using equipment
Think-Pair-Share
P
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Follow your teacher’s demonstration. Dissect a flower.
Observe and sketch the parts of a flower.
Research the name and function of each part of a flower.
Next, look at your classmate's flower. Can you find similar
flower parts in your classmate's flower?
du
ca
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on
Carpel
The carpel refers to the female
reproductive organ of the flower. It
consists of the stigma, style and ovary.
ls
to
n
E
During reproduction, pollen grains will
stick to the stigma.
If the reproduction process is
successful, the ovary will develop into a
fruit which contains seeds.
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20
23
A
The style is a tube that connects the
stigma to the ovary.
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The sepal is the outer
part of the flower
that protects the
flower bud before
the flower blooms.
Flower bud
Clues
Dissect – To cut open something and study its structure
Life Cycle of Flowering Plants
7
Solve this!
Which part of the flower attracts insects or small animals that will help
the plant to reproduce?
2 The part labelled X in the picture feels sticky.
Name Part X.
b Describe the function of Part X.
c Name the parts that make up
the stamen. Is the stamen the
male or female part of a flower?
a
k
kboo
or
Worksheet 2
ca
ti
W
on
P
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1
du
What are the key stages in the life cycle of a flowering plant?
2
ls
to
n
E
Just like animals, flowering plants have a life cycle too. Flowering plants go
through various stages in the life cycle again and again.
Let’s investigate!
yr
ig
h
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Materials:
20
23
A
t.
cycle of a flowering plan
life
e
th
of
es
ag
st
nt
re
Aim: To find out the diffe
C
op
Green bean seeds
8
Cotton pads
Instructions:
1 Watch a video on the life cycle of a flowering plant.
Take note of the following in the video:
Main stages in the life cycle of a flowering plant
Changes or parts that appear at each stage
Chapter 1
Pot of soil
Place a few green bean seeds on some cotton pads soaked with water.
Observe how the seeds develop over time.
3 Once you observe that the plant produces leaves, transfer the plant to a
pot of soil. Place the plant under the Sun and water it regularly. Observe
how the young green bean plant grows and develops flowers.
Do you think non-flowering
plants have the same life
cycle too?
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ig
h
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20
23
A
ls
to
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E
du
ca
ti
on
P
te
Questions:
1 What are the main stages in the life cycle of a flowering plant?
2 Draw what you observe at each stage. Label the new parts formed.
Describe their functions.
Lt
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2
Life Cycle of Flowering Plants
9
te
Lt
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The main stages in the life cycle of a flowering plant are seed, young plant and
adult plant.
on
P
Young plant
Adult plant
20
23
A
ls
to
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E
du
ca
ti
Seed
We can use a life cycle diagram to represent the life cycle of a flowering plant.
ig
h
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Solve this!
Name the main stages in the life cycle of a flowering plant.
2 Draw arrows to connect these different stages.
C
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1
10
Think-Pair-Share
What other models can we use to represent the life cycle of a flowering plant?
Chapter 1
P
te
Lt
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From a seed to a young plant
For a seed to develop into a young
plant, the seed needs to go through
a process known as germination.
Seed germination takes place at
the first stage of the life cycle of a
flowering plant.
ca
ti
on
Leaf
du
Germination process
E
Shoot
20
23
A
ls
to
n
Seed coat
The shoot
appears.
C
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ig
h
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The seed absorbs water and
swells. This breaks the seed coat
that covers the seed.
Once the seed coat is
broken, roots appear and
start growing downwards.
The seedling continues to grow. The
shoot grows to develop leaves. Now,
the plant uses the leaves to make
food. The plant is now a young plant.
Retrace our steps
What conditions
are required for
plants to grow
well?
What conditions are
needed for seeds to
germinate?
Life Cycle of Flowering Plants
11
3
Let’s investigate!
Place the wrapped seeds
into a resealable bag and
seal it. Label this bag ‘C’.
This is the control set-up.
Prepare three
bags of the
experimental
set-up.
te
5
3
P
Place the wrapped seeds
into a resealable bag and
seal it. Label this bag ‘E’. This
is the experimental set-up.
on
2
du
ca
ti
Instructions:
1 Soak a sheet of
paper towel with
water. Wrap five
cress seeds with the
wet paper towel.
Lt
d
n.
ed for seed germinatio
ed
ne
s
on
iti
nd
co
e
th
t
Aim: To find ou
Wrap five cress
seeds with a dry
paper towel.
7
Place Bags E and C in the following environments.
6
Prepare three
bags of the
control set-up.
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23
A
ls
to
n
E
4
yr
Inside a cupboard
that is dark and warm
C
Environment
Bag
Inside a cupboard that is dark and
warm
E
On a windowsill with light
and warmth
In a refrigerator that is dark
and cold
12
In a refrigerator that
is dark and cold
Predict how many seeds will germinate in the bags. Explain your predictions.
op
8
On a windowsill with
light and warmth
Chapter 1
C
E
C
E
C
Prediction
Inside a cupboard that is dark and warm
On a windowsill with light and warmth
Bag E
Bag C
Bag E
Bag C
0 2 4 6
0 2 4 6
0 2 4 6
0 2 4 6
Number of days
Number of days
Number of days
Number of days
du
ca
ti
on
P
Lt
d
Leave the bags of seeds in each environment for six days. Open each bag
and unwrap the paper towel every two days for observation. Count the
number of seeds that have germinated every two days. Record the results in
the dot plots below.
te
9
E
In a refrigerator that is dark and cold
Bag C
20
23
A
ls
to
n
Bag E
0 2 4 6
0 2 4 6
Number of days
Number of days
C
op
yr
ig
h
t
Questions:
1 Based on your observations, conclude which of the following is/are needed
for the seeds to germinate. Circle.
( Soil / Light / Warm environment / Cold environment / Water )
2
Suggest an improvement for the investigation. Explain.
________________________________________________________________
________________________________________________________________
Life Cycle of Flowering Plants
13
Lt
d
Seeds need water and the right temperature to germinate. Seeds do not need
light to germinate. They can germinate in the dark. Most seeds can germinate
in a warm environment. If the temperature of the environment is too hot, the
seeds will not survive and they may die. If the temperature of the environment
is too cold, the seeds will not have enough energy to grow.
Think-Pair-Share
P
te
Plants need light to grow. Why is light not needed for seeds to germinate?
ti
on
To grow well, plants also need other nutrients. Once the seed has germinated
into a seedling, it can be transferred and planted into the soil. Some nutrients
can only be obtained from the soil.
E
du
ca
From a young plant to an adult plant
With the right conditions and nutrients, a young plant will develop and grow
into an adult plant. When the plant matures and starts to produce flowers, it is
ready to reproduce.
ig
h
t
Young plant
20
23
A
ls
to
n
Flower
Adult plant with flowers
Adult plant
A young plant developing into an adult plant
Fruit
yr
From an adult plant to a seed
In adult plants, reproduction
takes place in the flowers. After
reproduction, flowers develop into
fruits and seeds. Seeds can grow
into new plants.
Seed
Adult plant with fruits
14
Chapter 1
W
C
op
Fruit
k
kboo
or
Worksheets 3 & 4
What happens during reproduction in flowering plants?
on
P
te
Lt
d
Pollination
Pollination is the first step in the reproduction process. Successful pollination
occurs when pollen grains are transferred from the anther to the stigma of the
flower from the same kind of plant.
ca
ti
Plants cannot move
from one place to
another.
Methods of pollination
du
Think-Pair-Share
ls
to
n
E
Using the Internet or books, research to find out how pollen grains are transferred.
Use the guiding questions below:
How do insects or small animals transfer pollen grains?
What are some examples of these insects or small animals?
What are the other methods of pollination?
20
23
A
Pollination can be carried out by insects, other small animals and wind. When
animals such as bees, butterflies or hummingbirds are feeding at the flowers,
pollen grains can get onto their bodies. As these animals fly from flower to
flower, pollen grains are transferred. Wind can also help to carry the pollen
grains of some flowering plants.
C
op
yr
ig
h
t
Pollen grain
Watch this video to
see how the bumblebee buzzes and
shakes the pollen grains out of a flower.
Can you spot the pollen grains on the bee’s
body in the video?
Pollen
grain
Pollen basket
Pollen grain
Tiny pollen grains
will attach to the hairy body
of the honey bee. The pollen
grains will get rubbed off
the bee's body when it visits
another flower.
Life Cycle of Flowering Plants
15
A
pollen grain lands
on the stigma.
2
T
he sugary substance
on the stigma helps
the pollen grain to
grow a pollen tube.
ca
ti
T
he pollen tube grows and
extends through the centre of
the style towards the ovary.
4
T
he ovary
contains the egg
of the flower.
A
ls
to
n
E
du
3
on
P
te
1
Lt
d
Process of fruit and seed production
After successful pollination. the reproduction process continues in the stigma
of the flower. The pollen grain develops a pollen tube that grows into the ovary.
After fertilisation, the
flower starts to wither.
C
op
yr
ig
h
t
20
23
In the ovary, fertilisation takes place. The ovary develops into a fruit, while the
egg develops into a seed.
The petals fall off. Seeds
are formed in the ovary.
The ovary swells and starts
to develop into a fruit.
16
Chapter 1
Fruit
The fruit grows bigger.
Fertilisation – In plants, it is the process where a pollen grain meets with an egg in the
ovary before forming fruit and seeds
W
Clues
Seed
k
kboo
or
Worksheet 5
Think-Pair-Share
Lt
d
Observe and cut the fruit given to you. Identify the seeds within the fruit.
Draw a well-labelled diagram to indicate the seeds within the fruit.
Why does a plant grow fruits?
te
What is the difference between a fruit and a seed?
on
What about
peas? Are they
fruits?
ls
to
n
E
du
ca
ti
Is peanut
a fruit?
P
Watch out!
Fruit
Seed
ig
h
t
20
23
A
Fruits are plant structures that contain seeds. Some fruits
have only one seed while others have many seeds. There
are different types of fruits. Some can be eaten while
others cannot. Not all fruits are sweet, juicy and fleshy
like apples and mangoes. Some fruits such as peanuts
can be dry. Others are inedible like the angsana fruit.
Solve this!
What do seeds need to germinate successfully?
2 Which part of the plant appears first during germination?
3 Where does fertilisation take place in a flowering plant?
4 After fertilisation, which part of the plant develops into a seed? Which
part of the plant develops into a fruit?
C
op
yr
1
Clues
Inedible – Not suitable to be eaten as food
Life Cycle of Flowering Plants
17
C
op
yr
ig
h
t
ti
ca
du
20
23
A
ls
to
n
E
We are botanists. We study about
plant parts and their functions.
We observe how plants grow and
investigate what are needed for
them to grow.
on
P
te
Lt
d
Science in context
18
Chapter 1
We are gardeners. We keep the
plants in a garden healthy and
maintain the beauty of the garden.
To do our job well, we need to know
the right conditions for plants at
each stage of their life cycle.
Adult plant
Life Cycle of
Flowering Plants
Seed
Lt
d
Crack the case
Goes through
____________
to become
Flower
ca
Carpel
___________
___________
du
Stamen
ti
on
produces
P
te
Young plant
Style
Fruit
Fruit
Seed
E
Filament
found in
ls
to
n
Ovary
which can undergo
produced
from
successful pollination
leads to
20
23
A
Pollination
Transfer of pollen grains from ______to ______
Fertilisation
Occurs when a pollen
grain meets with an
egg in the ovary
yr
ig
h
t
Can be pollinated by __________ or ________
Place them into the soil. Do not water them.
Place them under the Sun. Water them regularly.
Place them in the fridge. Water them regularly.
P
lace them in the fridge. Do not water them.
W
C
op
What should Ada do to grow her seeds? Tick (✓).
k
kboo
or
Consolidation worksheet
Life Cycle of Flowering Plants
19
Adaptations of Plants
P
te
Lt
d
CHAPTER 2
C
op
yr
ig
h
t
20
23
A
ls
to
n
The butterflies are so
pretty! I am going to
catch them to keep as
pets at home!
E
du
ca
ti
on
Why are there
no fruits on my peach
plants? What should I do
so that my plants can
produce fruits?
20
Chapter 2
What Will I Learn
✓ Describe how flowering plants are adapted to
attract pollinators.
✓ Describe seed dispersal and how plants are adapted
for seed dispersal.
✓ Describe how plants are adapted to environments that
are hot, cold, wet or dry.
What processes
need
to occur for a plan
t to
produce fruits? C
an these
processes occur
in Vera's
peach plants? W
hy?
What features do the
flowers on Vera's peach
plants have? How do
these features help the
plants produce fruits?
What are adaptations?
Lt
d
Adaptations are special features that help animals and plants
to thrive in their environments. Different plants have different
adaptations that help them become suited to their environment. This
allows them to live and grow well.
E
du
ca
ti
on
P
te
Look at the three different environments in the pictures below. Can
you guess the types of environment the plants are living in?
ls
to
n
Plants living in hot and dry
In cold climates, plants have
Plants that live in water
environments have adaptations features to protect themselves have adaptations to make
to protect themselves from the from the cold.
sure they can continue to
heat and from losing water.
obtain sunlight.
20
23
A
To thrive, plants need to be able to reproduce too. Plants also have
adaptations to help them in pollination and seed dispersal.
ig
h
t
Do you
remember what
pollination is?
C
op
yr
How are plants adapted for pollination?
Flowering plants can have adaptations so that they can be
pollinated by animals or wind.
Adaptations to attract pollinators
Insects and other animals that help plants to pollinate are known as
pollinators. Flowers have features to attract pollinators.
Adaptations of Plants
21
1
Let’s investigate!
te
Instructions:
1 Take a walk around your school. Observe the flowering plants.
Lt
d
ring plants that help to
we
flo
in
ns
tio
ta
ap
ad
e
Aim: To find out th
attract pollinators.
Choose two flowering plants. Draw diagrams of the flowers on each plant.
Label the features that you think may help attract pollinators.
3
Identify all the pollinators that are visiting the flowering plants.
ls
to
n
E
du
ca
ti
on
P
2
C
op
yr
ig
h
t
20
23
A
Questions:
1 Describe the common features of the flowers that were visited by pollinators.
2 Choose two features. How do the features help the flowers
attract pollinators?
22
Adaptations of flowering
plants to attract pollinators
Chapter 2
Some petals have bright
colours and pleasant
smells to attract
pollinators to the flowers.
Some flowers produce nectar
which is a sweet and sugary
substance. Pollinators go to
the flowers to feed on nectar.
How are
wind-pollinated plants
adapted for pollination?
on
P
te
Lt
d
Adaptations for wind pollination
Plants that depend on wind to carry their pollen grains usually produce more
pollen grains than plants that are pollinated by pollinators.
The pollen grains of wind-pollinated plants are tiny and light. This allows the
pollen grains to be carried away by the wind easily.
The stigmas of
wind-pollinated
plants are usually
large and feathery.
ca
ti
The stamens of these
plants are usually long
and extend out of the
flower.
This allows the
stigmas to catch the
pollen grains in the
air easily.
ls
to
n
E
du
This exposes the
stamens to the wind
and allows pollen grains
to be carried away by
the wind easily.
Adaptations of flowers of wind-pollinated plants
For plants that depend on pollinators to pollinate their flowers, describe two
adaptations that help them.
20
23
1
A
Solve this!
________________________________________________________________
For plants that depend on wind to pollinate their flowers, describe two
adaptations that help them.
________________________________________________________________
________________________________________________________________
W
C
op
yr
2
ig
h
t
________________________________________________________________
k
kboo
or
Worksheet 1
Adaptations of Plants
23
What is seed dispersal?
Retrace our steps
In the life cycle of
a flowering plant,
what is the stage that
comes after the
adult stage?
Think-Pair-Share
Lt
d
How did the dandelion plant get there?
ca
ti
on
P
te
These flowers were not
here a few weeks ago.
ls
to
n
E
du
After the fruits and seeds have matured, the parent plant will have to transfer
its seeds away. The process of transferring seeds away from the parent plant
is known as seed dispersal.
Think-Pair-Share
C
op
yr
ig
h
t
20
23
A
Seeds that are grown too close to the parent plant do not grow well after they have
germinated. Seeds that are grown further away from the parent plant tend to grow more
healthily. Why? Using the Internet or books, research and discuss your findings.
24
Seeds that grow close
to the parent plant
Seeds that grow further
away from the parent plant
Plants disperse their seeds so that the young plants grow in places further
away from the parent plant. This helps the young plants avoid competition for
light, water and nutrients with the parent plant or other young plants. With less
competition, the young plants are more likely to survive.
Chapter 2
How are the seeds of the following plants dispersed?
Dandelion
Lt
d
Coconut tree
Coconut fruit
on
P
te
Seed
The seed is found inside the
coconut fruit.
ti
The seeds are found on the
seed head of the dandelion.
Pea plant
du
ca
Mango tree
ls
to
n
E
Seed
20
23
A
The seeds are found in the pea pod,
which is the fruit of the pea plant.
C
op
yr
ig
h
t
Oak tree
Mango
fruit
The seed is found inside the
mango fruit.
Goosegrass
Acorn
nut
The seed is found in the acorn nut,
which is the fruit of the oak tree.
Fruit
with
hooks
The seed is found inside the
goosegrass fruit.
Think-Pair-Share
Using the Internet or books, research to find out how the seeds of the above plants are
dispersed. Present your findings.
Adaptations of Plants
25
How do plants disperse their seeds?
ti
20
23
A
ls
to
n
E
du
ca
By water
Some plants depend on
moving water to disperse their
seeds.
on
P
te
Lt
d
By wind
Some plants depend on
the wind to disperse their
seeds.
C
op
yr
ig
h
t
By animals
Some plants depend on
animals to help carry
the seeds away from the
parent plant.
26
Chapter 2
By exploding or
splitting open
Some plants disperse their
seeds by splitting open
their fruits. Others do so by
exploding their fruits.
How are plants adapted to disperse their seeds?
on
P
te
Lt
d
Adaptation for seed dispersal by water
The fruits or seeds of these plants are usually round.
It helps them roll into water easily. The fruits or seeds
can trap air so that they can float on water.
ls
to
n
E
du
ca
ti
Adaptation for seed dispersal by wind
The fruits or seeds of these plants are light. They usually
have shapes that look like wings or parachutes.
Adaptation for seed dispersal by animals
The fruits or seeds of these plants are
sweet and fleshy or are high in nutrients.
These attract animals to feed on them.
Some plants have hooks on their fruits so
that the fruits can attach themselves to
the animal’s fur easily.
C
op
yr
ig
h
t
20
23
A
Adaptation for seed dispersal by
exploding or splitting open
When the seeds are fully grown,
the fruit dries out and explodes or
splits open, scattering the seeds
away from the plant.
Adaptations of Plants
27
2
Let’s investigate!
Lt
d
for
seeds with adaptations
d
an
its
fru
of
s
el
od
m
Aim: To create
nt environments.
seed dispersal in differe
Aluminium foil
Different types of paper
on
P
te
Materials:
Hook-and-loop fasteners
Sticky tape
A
ls
to
n
E
du
ca
ti
Instructions:
1 Build a model of the fruit or seed of a plant that is likely to be found in the
environment assigned to you.
20
23
A beach
An open field
A tropical rainforest
Compare your model with the actual photographs of the fruit or seed
of the plant living in that environment.
3 Compare your classmates' models with the actual photographs of the
fruit or seed.
ig
h
t
2
op
yr
Question:
Explain how each plant is adapted to disperse its seeds in each environment.
C
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
28
Chapter 2
Solve this!
Lt
d
Describe and explain an
adaptation for plants with
seeds that are dispersed by
animals.
Predict the seed dispersal method for the
seed shown below. Explain your answer.
te
2
3
P
Plant X disperses its seeds
by water. What is a possible
feature that the fruit or seed
of Plant X has?
k
kboo
or
Worksheet 2
on
W
1
ca
ti
What other adaptations do plants living in different environmental
conditions have?
du
Plants need to have other adaptations that allow them to make food, obtain
water or store water in their natural environment so that they can thrive, grow
and reproduce.
Cacti are usually found in the desert. What
features do they have?
How do these features help them survive in
the desert?
ls
to
n
Hot and dry environment
E
Think-Pair-Share
C
op
yr
ig
h
t
20
23
A
Plants living in a hot and dry
environment usually have small
leaves or leaves that look like sharp
spines. Some also have large, green stems to help them make food using light
from the Sun.
Barrel cactus
Pancake prickly pear cactus
Saguaro cactus
These spine-like leaves help the plant to reduce water loss and conserve
water. The sharp leaves also prevent animals from eating the plants. Many
of these plants have thick, fleshy stems to store water too. They have a waxy
coating on the stems to prevent water loss.
Adaptations of Plants
29
Water stored in
the form of gel
Instead of spine-like leaves, some plants like the
aloe vera have thick, fleshy leaves to store water.
P
te
Lt
d
Some plants living in a hot and dry environment
have shallow roots near the surface of the soil.
They are widely spread out to absorb water near
the soil surface. Some other plants develop deep
roots. These roots grow deep underground
to obtain water from far below the soil surface.
on
Aloe vera
Water lily
ls
to
n
E
du
ca
ti
Living in water
These plants usually have large leaves to get more sunlight to make food.
Bulb-like
stem that
can trap air
Water hyacinth
20
23
A
Some plants living in water have parts that can trap air. These parts enable the
plants to float so that their leaves can get more sunlight to make food.
yr
ig
h
t
Cold and dry environment
Plants living in an extremely cold environment have small, narrow leaves to
reduce water loss.
C
op
Short,
needle-like
leaves
Spruce trees
Some plants grow close together near the ground so that they are less exposed
to the wind and snow. These plants usually have shallow and widespread roots
to obtain water from the frozen surface.
30
Chapter 2
3
Let ’s investigate!
Leaf
P
Stem
Leaves
A
C
E
Predict the environment these plants live in. Choose from the following:
ls
to
n
2
B
du
ca
ti
on
Leaf
te
Instructions:
1 Describe the features of the following plants. Your teacher will
provide a list of guiding questions to help you.
Lt
d
to
ns of plants that allow them
Aim: To identify the adaptatio
survive in an environment.
In water
Dry environment
A
Question:
For each plant, explain how its features help the plant adapt to the
environment you have chosen.
20
23
_________________________________________________________________
_________________________________________________________________
ig
h
t
_________________________________________________________________
Solve this!
Plant Y lives in a hot and dry environment. Describe one
adaptation that it needs to help it survive.
yr
2
Ada is holding a type of plant shown on
the right. Predict the environment that
this plant lives in. Explain.
Bulb-like
part
W
C
op
1
k
kboo
or
Worksheet 3
Adaptations of Plants
31
Science in context
Think-Pair-Share
20
23
A
ls
to
n
E
du
ca
ti
on
P
te
Instead of waiting for plants to disperse their fruits and seeds naturally,
farmers and gardeners grow plants by planting the seeds in soil.
Lt
d
How will the tall buildings in our environment affect plant growth and seed dispersal?
C
op
yr
ig
h
t
We can spray
pesticides to kill pests
that feed on our plants.
32
Chapter 2
Will pesticides kill the
pollinators too? Watch
the following video to
find out more.
Crack the case
Live in different environments
so that plants can
Reproduce
Seed dispersal
Pollination
P
in
environments
that are
te
which involves
Make food or obtain water
It is the process of
transferring _____ away
from ______ plant.
on
by
ca
ti
Wind or _______
by
du
In _______
Wind
_____________
_____________
or splitting open
Water
ig
h
t
A
20
23
Cold and dry
ls
to
n
E
_____
and dry
are features
which help
plants to
Lt
d
Plant Adaptations
fruits? Tick (✓).
the peach plants.
Remove the net covering
r.
Grow the plants near wate
near her plants.
Allow bees and birds to go
butterflies in her garden.
g
hin
tc
ca
op
st
to
a
Ad
k
As
W
C
op
yr
at her plants can produce
What should Vera do so th
y place.
Grow the plants in a wind
k
kboo
or
Consolidation worksheet
Adaptations of Plants
33
CHAPTER 3
Solids, Liquids and Gase
te
Why has the shampoo stopped flowing
into the bottle? What should I do to get
the rest of the shampoo in quickly?
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
on
P
Cyrus is helping his mother
to
fill an empty plastic bottle wit
h
shampoo. To secure the fun
nel
to the bottle while pouring in
the
shampoo, he seals the funne
l to
the bottle with sticky tape.
Lt
d
s
✓ Name the common gases at room temperature.
✓ Describe solids, liquids and gases using the particle model.
C
op
yr
What Will I Learn
34
What was in the
plastic bottle before
Cyrus tried to fill it
with the shampoo?
Chapter 3
What are
the properties of
the matter in the
plastic bottle?
Why did some
shampoo manage to
enter the bottle while
the rest pooled at
the funnel?
What are the gases around us?
Do you
remember some
of the common
solids, liquids or
gases?
Solids, liquids and gases are three states of matter.
Let’s investigate!
Lt
d
1
P
on
ca
Instructions:
1 Using the Internet or books, research
the substances above.
2 What are their states of matter at
room temperature (25 ºC)? Classify
the substances into solids, liquids or
gases using a table as shown.
Oxygen
Hydrogen
ti
Materials:
Cards showing the following substances:
Water
Iron
Nitrogen
Steel
Vinegar
Carbon dioxide
te
s.
solids, liquids and gase
to
in
es
nc
ta
bs
su
on
m
Aim: To classify com
Liquid
Gas
ls
to
n
E
du
Solid
2
20
23
A
Questions:
Do you think gases have a
1 Look at the gases you have classified.
fixed shape or volume?
a Do they have a colour? _______________
b Do they have a smell? _______________
What properties do all the gases have in common?
ig
h
t
Think-Pair-Share
C
op
yr
Look at your table again. Will the substances be classified differently if the surrounding
temperature becomes very high or very low? Which substance may change state if we move
it from room temperature to the freezer?
There are many gases around us. The air around us contains mainly
nitrogen, oxygen, carbon dioxide, hydrogen and water vapour. Water
vapour is water in gaseous state.
We breathe out carbon
dioxide and water vapour.
They are waste materials
produced by our body.
We take in
oxygen from
the air to
stay alive.
Oxygen
Carbon
dioxide
Water vapour
Solids, Liquids and Gases
35
What are the uses of different gases?
Science in context
We use carbon dioxide
gas in the fire extinguisher
to put out a fire.
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
on
P
te
Lt
d
During a dental surgery, we
use anaesthetic gases to help
patients manage pain. After
breathing in the gas, the patient
will not feel pain.
Clues
36
Chapter 3
Anaesthetic - A substance that can make you unable to feel pain
on
P
te
Lt
d
Nitrogen and hydrogen
gases are used to make
fertilisers. Fertilisers help
plants to grow well!
I drive a hydrogen fuel
cell car. The car runs on
hydrogen fuel which uses
hydrogen gas!
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
We need oxygen gas to
breathe underwater. Oxygen gas
is stored inside an oxygen tank
which we can carry on our back
when diving underwater.
Think-Pair-Share
What are the uses of gases in Let's Investigate 1? Using the Internet or books, research their
uses. Share your findings with your class.
Solids, Liquids and Gases
37
Solve this!
1
Match each gas to its correct use.
Living things breathe in
this gas to stay alive.
We use it to make fertilisers.
Oxygen
We use it to put out fires.
Hydrogen
We use it to fuel some cars.
ti
on
P
te
Nitrogen
Name the gases found in air.
_______________________________________________________________
W
Worksheet 1
ls
to
n
What are the properties of gases?
k
kboo
or
E
du
ca
2
Lt
d
Carbon dioxide
Think-Pair-Share
A
How do we know that gases exist?
Use a straw to blow some air into a cup of water.
What did you observe? What are inside these bubbles?
C
op
yr
ig
h
t
20
23
Many gases are colourless and do not have a smell. We cannot see or easily
tell that these gases are around us.
38
Chapter 3
What gases do
you think are inside
my balloons?
Are the properties of
gases similar to the
properties of solids or
liquids? What are the
properties of solids and
liquids?
Gases occupy space
2
Let ’s investigate!
Materials:
Container of water
Lt
d
Aim: To show that gases take up space.
Kitchen towel
P
te
Cup
ti
on
Instructions:
1 Push a piece of kitchen towel to the bottom of a cup and compress it.
du
ca
Cup
Invert the cup and push it into a container of water.
3
Kitchen towel
Water
Container
20
23
A
ls
to
n
2
E
Kitchen towel
Remove the cup from the water. Check the kitchen towel.
C
op
yr
ig
h
t
Questions:
1 Did the kitchen towel get wet after we pushed the inverted cup into the
water? ____________
2 Besides the kitchen towel, what else was in the cup? ____________
3 What can you infer from your observation?
Air ____________ space. The kitchen towel (got / did not get) wet because
water (could / could not) fill up and reach the towel in the cup.
There is air in the cup. Air contains gases and gases occupy space in the cup.
When we push an inverted cup into the water, gases in the cup prevent water
from filling up and reaching the kitchen towel in the cup. Therefore, the towel
inside the cup remains dry.
Solids, Liquids and Gases
39
Gases do not have a fixed volume
Let’s investigate!
3
Lt
d
s can be compressed.
Aim: To find out if gase
P
te
Material:
Syringe
du
ca
ti
on
Instructions:
1 Draw some air into a syringe. What is the volume of air in the syringe?
____________ ml
2 Cover the opening of the syringe with your finger. Push the plunger in.
What is the volume of the air in the syringe now? ____________ ml
ls
to
n
E
Questions:
What happens to the volume of the air in the syringe when you push the plunger
in? Can air be compressed?
_____________________________________________________________________
20
23
A
Gases do not have a fixed
volume. This means that a
gas can be compressed and
we can reduce its volume.
Liquids and solids
cannot be compressed as
their particles are packed
closely together. How do you
think the particles in a gas
are arranged?
C
op
yr
ig
h
t
Gases can flow and fill up the space in the container.
So, gases can take the volume of the container that they are in.
Volume of air in syringe: 100 ml
Volume of air in container: 0 ml
Volume of container: 200 ml
Volume of air
in syringe: 0 ml
Volume of air in
container: 200 ml
When 100 ml of air is added to an empty 200 ml container, the air flows and fills up
the space in the container. The volume of air in the container becomes 200 ml.
40
Chapter 3
Gases do not have a fixed shape
Do gases take the shape of a container or do they have fixed shapes like solids?
Try blowing air into balloons of different shapes. What do you notice?
ti
on
Retrace our steps
How are particles
arranged in solids
and liquids? Draw.
ca
Just like solids and liquids, gases are made up of tiny
particles too.
Worksheet 2
P
How do we use the particle model to describe solids,
liquids and gases?
k
kboo
or
te
W
Gases do not have a fixed shape. They flow and take the shape of the
container that holds them.
Lt
d
Think-Pair-Share
E
ls
to
n
Do you think the arrangement of the
particles in gases is similar to solids and
liquids? How do you think particles are
arranged in gases? Draw.
du
Think-Pair-Share
20
23
A
Consider the movement of particles in
each state of matter. Which state of matter
has particles with the greatest amount of
energy? Which state has particles with the
lowest amount of energy?
Particle
Energy of particles increases
C
op
yr
ig
h
t
Gas particles are spaced very far apart from one another.
The particles move quickly and freely in all directions.
Solid particles vibrate at
their fixed positions. They
have the least amount of
energy.
Liquid particles can move
around or slide past one
another. They have more
energy than solid particles.
Gas particles move very quickly
and randomly in all directions. They
have a higher amount of energy
compared to the particles in solids
and liquids.
Solids, Liquids and Gases
41
P
te
Solid particles cannot move around
one another freely. The particles can
only vibrate at their fixed positions.
Hence, solids have a fixed shape and
cannot flow like liquids.
The shape of the ice cubes remains
unchanged when we transfer the ice
cubes from one container to another.
A
Ice is water in solid state. Ice in the
syringe cannot be compressed.
ls
to
n
E
du
ca
ti
on
Solid
Solid particles are very closely
packed together. There is very
little space between the particles.
Therefore, solids have a fixed
volume and cannot be compressed.
Lt
d
How do we use the particle model to explain the properties of solids,
liquids and gases?
Liquid
Liquid particles can move around or
slide past one another. So, liquids can
flow and take the shape of a container.
C
op
yr
ig
h
t
20
23
Liquid particles are closely packed
together. Hence, liquids have a fixed
volume and cannot be compressed.
Water in the syringe cannot be compressed.
42
Chapter 3
Water changes its shape and takes
the shape of the container that it is in.
Lt
d
Gas particles move very quickly and
randomly in all directions. Just like
particles in liquids, they can flow and
take the shape of any container that
holds them.
Solve this!
E
A
Cyrus has 100 ml of a substance that is blue in colour. He transfers it into a
200 ml transparent container. Now, the substance has taken the shape of the
new container. It has also made the whole container look blue.
20
23
1
Air particles in the syringe flow into the
beaker and take the shape of the beaker.
ls
to
n
When we compress air, air particles move
closer to one another.
du
ca
ti
on
P
te
Gas
Gas particles are very far apart from
one another. There is a lot of space
between the particles. Therefore,
gases can be compressed and they
do not have a fixed volume.
ig
h
t
What is the state of this substance? Explain your answer using the properties
of this substance.
________________________________________________________________
yr
________________________________________________________________
Cyrus fills a syringe with 20 ml of helium gas. He tries to compress the
helium gas in the syringe. He seals the opening of the syringe and pushes in
the plunger.
Can the plunger be pushed in? Why or why not?
_________________________________________________________________
W
C
op
2
k
kboo
or
Worksheet 3
Solids, Liquids and Gases
43
Crack the case
Lt
d
Solids, Liquids and Gases
ti
on
P
te
Particle model
Liquid
du
E
______________
or slide past one
ions
posit
________
another
__________ at
______________
and randomly in
all directions
20
23
A
Movement of
particles
Gas
_______________ _______________ _______________
packed
packed
ls
to
n
Arrangement of
particles
ca
Solid
Gas
C
op
yr
ig
h
t
Solid
44
Chapter 3
Liquid
such as
Water vapour
xide
Carbon dio
Lt
d
Gases
have
ti
ca
Occupy space
du
so
Gases can take the
volume of a container
No fixed shape
so
Gases can take the
shape of a container
20
23
A
ls
to
n
E
Gases can be
compressed
P
on
have
can
No fixed volume
Nitrogen
en
Hydrog
Properties
have
te
Oxyg
en
W
C
op
yr
ig
h
t
(✓).
o the bottle quickly? Tick
int
o
po
am
sh
e
th
t
ge
to
e
What should Cyrus do
flow from the funnel into th
o
po
am
sh
e
th
let
d
an
it
Cyrus should wa
bottle.
w
allow more shampoo to flo
to
ad
te
ins
el
nn
fu
er
gg
bi
Cyrus should use a
into the bottle.
e and the funnel. He can
ttl
bo
e
th
s
al
se
at
th
pe
ta
e.
Cyrus can remove the
the shampoo into the bottl
s
ur
po
he
as
up
el
nn
fu
e
slightly lift th
k
kboo
or
Consolidation worksheet
Solids, Liquids and Gases
45
CHAPTER 4
Changing States of Wate
It is a very hot day.
Vera is making some
ice lollies for Coco.
Lt
d
r
E
du
ca
ti
on
P
te
I hope Coco likes
ice lollies.
ls
to
n
After a few hours....
C
op
yr
ig
h
t
20
23
A
What happened to my
ice lollies?
What should I do?
What Will I Learn
✓ Describe the main properties of water and how water acts
differently from many other substances.
✓ Use the particle model to describe evaporation and
condensation and relate these processes to changes in
temperature.
46
Chapter 4
ess
What proc
ater
changes w
to
from liquid
solid?
What happens
to the volume
of water after
this process?
Why is water special?
Retrace our steps
What substance on the Earth exists in all three states naturally?
What are the
three states of
matter?
Lt
d
Think-Pair-Share
ls
to
n
E
du
ca
ti
on
P
te
Water is a unique substance. It is the only substance that we can
commonly find as a solid, liquid and gas on Earth.
Different parts of the Earth can have different temperatures.
In very cold places on Earth, we can find water as a solid.
A
Ice is water in solid state.
Snow is water in solid state too.
C
op
yr
ig
h
t
20
23
In most parts of the Earth, we can find water as a liquid or gas.
We can find water in liquid form in rivers, lakes, seas and oceans.
Clues
Unique – Unusual or the only one of its type
Changing States of Water
47
Lt
d
In the sky, we can find water as a
liquid too. Clouds in the sky are made
up of tiny water droplets. These
water droplets are water in the
liquid state.
on
ti
ca
du
E
ls
to
n
Water can be found as a gas in the air.
It is called water vapour. The amount of
water vapour in the air can change. When
the amount of water vapour in the air
is high, we say that the humidity of the
surroundings is high. When the amount of
water vapour in the air is low, we say that
the humidity of the surroundings is low.
P
te
We can find water in three
states on Earth. This is what
makes water so special!
Solve this!
A
Give an example of water in each of its three different states.
20
23
What are the melting point and freezing point of water?
ig
h
t
Melting point of water
During the process of melting, water changes state from
solid to liquid.
C
op
yr
The ice cubes are
getting smaller and
some water is forming
in the bowl. What is
happening?
Clues
48
Chapter 4
Humidity – The amount of water vapour that the air can hold
Retrace our steps
What will happen to an
ice cube if we leave it out at
room temperature?
What causes the change?
What is the name of the
process?
Let’s investigate!
1
Materials:
Beaker
Ice cubes
Thermometer
Lt
d
melts.
perature of ice when it
m
te
e
th
t
ou
d
fin
To
:
m
Ai
on
P
te
When measuring temperature,
we need to make sure that the
bulb of the thermometer is fully
covered by the ice cubes.
Bulb
Place the beaker of ice at room temperature. Ice melts when it changes
from a solid to a liquid. Start recording the temperature of the ice every two
minutes the moment you see water forming in the beaker.
Time (min)
4
20
23
6
Temperature of the ice (ºC)
A
2
ls
to
n
E
2
du
ca
ti
Instructions:
1 Fill half a beaker with ice cubes. Put the
thermometer into the beaker of ice.
Record the temperature of the ice. ______ ºC
Did the temperature of the ice increase as it was changing from a solid to
a liquid?
______________________________________________________________
C
op
yr
2
ig
h
t
Questions:
1 What was the temperature of the ice when you observed water forming in
the beaker?
________________________________________________________________
Conclusion:
The temperature at which ice changes from a solid to a liquid is _____ ºC.
Changing States of Water
49
Lt
d
When we take ice out from the freezer and place it at room temperature
(25 ºC ), it gains heat. As ice gains heat, its temperature increases. When the
temperature of the ice reaches 0 ºC, it starts to melt and changes into a liquid.
At 0 ºC, ice starts
to melt. The
temperature of ice
remains at 0 ºC
during melting.
on
P
te
The ice cubes in
this beaker are
getting warmer
and starting to
melt.
ca
ti
Melting of ice cubes
du
The temperature at which ice melts is known as the
melting point of water. The melting point of water is 0 ºC.
ls
to
n
E
Freezing point of water
During the process of freezing, water changes state
from liquid to solid.
Think-Pair-Share
Retrace our steps
How do we change
water to ice?
What is the name
of the process?
20
23
A
Freeze some water. Measure and record the temperature of water when you start to see water
turning into ice. What is the temperature at which water changes from a liquid to a solid? _____ºC
Note the temperature of water every two minutes. Did the temperature change?
Freezing of water
yr
ig
h
t
When water is placed in the freezer, it is cooled. As water cools, it loses heat
and its temperature starts to drop. When the temperature of the water drops
until it reaches 0 ºC, water starts to freeze or solidify and changes into a solid.
C
op
The temperature
of water starts to
decrease when we
place the water in
the freezer.
50
Chapter 4
At 0 ºC, water
starts to freeze. The
temperature of water
remains at 0 ºC
during freezing.
The temperature at which water freezes is known as the freezing point of
water. The freezing point of water is 0 ºC.
Melting at 0 ºC
Freezing at 0 ºC
te
Do you notice anything
about the melting point
and freezing point of
water?
Lt
d
The melting point and freezing point of water are properties of water.
When the surrounding
temperature is above
0 ºC, ice starts to melt.
We find water as liquids in
this environment.
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
on
P
They are the
same!
When the surrounding
temperature is below 0 ºC,
water starts to freeze. We
find water as solids in this
environment.
Changing States of Water
51
What happens to the volume of water when it freezes?
Let’s investigate!
water when it freezes.
of
e
m
lu
vo
e
th
to
s
en
pp
Aim: To find out what ha
P
on
E
du
ca
ti
Instructions:
1 Fill half a plastic bottle with
water. Mark the water level on
the outside of the bottle with
a marker.
te
Materials:
A plastic bottle that is cut in half Water
Different coloured markers Freezer
Place the bottle in a freezer. Predict what will happen to the water.
________________________________________________________________
3
Observe the bottle in the freezer every 30 minutes. Note what happens to
the water in the bottle. Are there any changes in the water level?
yr
ig
h
t
30
20
23
A
ls
to
n
2
Time (min)
C
op
60
90
52
Lt
d
2
Chapter 4
Describe what you observed.
Draw what you observed.
Observe the bottle in the freezer again the next day.
What happens to the water in the bottle after a day in the freezer?
________________________________________________________________
5
Mark the ice level on the outside of the bottle with a different coloured marker.
Lt
d
4
E
du
ca
ti
on
P
te
Question:
Compare the markings made on the bottle in Step 1 and Step 5. What can you
say about the volume of water after it freezes to become ice?
___________________________________________________________________
ls
to
n
When substances are
placed in containers of the
same size and shape, we
can use the heights of the
substances to compare
their volumes.
op
yr
ig
h
t
20
23
A
The water in Bottle A has
a greater height than the
water in Bottle B. This tells
us that the volume of water
in Bottle A is greater than
the volume of water in
Bottle B.
Height
C
Height
Bottle A
Bottle B
Changing States of Water
53
du
ca
ti
on
P
te
Lt
d
When water freezes, its volume increases and it expands by about nine
percent. This is another property of water. It is one of the few substances on
Earth that expands when frozen.
E
During winter, water
in the water pipe
may freeze. What
problems will this
cause?
C
op
yr
ig
h
t
20
23
A
ls
to
n
What causes
these bricks to
crack?
Ice floats on top of the water.
54
Chapter 4
What happens to
the water in the lake
during winter?
During winter, the temperature in the surroundings drops. Water near the
surface of the lake will cool and freeze when its temperature reaches 0 °C.
te
Lt
d
Water on the surface of the lake becomes ice. Ice floats on top of the water in
the lake. Below the layer of ice, water remains as liquid. Fish can continue to live
in the liquid water beneath the frozen surface of the lake during winter.
Wow, the fish are
still alive. Why are
they not frozen?
ls
to
n
E
du
ca
ti
on
P
Be careful, Vera!
You may cause the
ice under your feet
to crack! You may
end up in deep and
cold water!
20
23
A
What has happened
to your drink?
Think-Pair-Share
ig
h
t
What has happened to Ada's drink? Discuss with your classmates.
Solve this!
What is the melting point of water?
2 What is the freezing point of water?
3 Jack filled up an ice cube tray full of water and covered the tray with a
loose-fitting cover. He puts the ice cube tray in the freezer.
After a day, Jack found that the tray cover has popped out of the tray.
What has happened?
W
C
op
yr
1
k
kboo
or
Worksheet 1
Changing States of Water
55
What happens when water is heated?
Think-Pair-Share
Heat some water until it reaches 100 ºC.
What did you observe?
te
on
P
What can you
see forming in the
water when water
reaches 100 ºC?
What rises to the
water surface when
water is at 100 ºC?
ca
ti
What happens to
the water as it is
heated?
Be careful! You
should stand at a safe
distance away from the
hot water.
Lt
d
Boiling point of water
When a liquid is heated, it can turn into a gas. This process is known as boiling.
du
Thermometer
E
Beaker
ls
to
n
Water
20
23
A
As water gains heat, its temperature starts to increase. When the temperature
of water reaches 100 ºC, water starts to boil and changes state from liquid to
gas. This gas is known as water vapour.
ig
h
t
The water in this
beaker is starting
to boil!
C
op
yr
During boiling, the
temperature of
water remains at
100 ºC.
Boiling of water
The temperature at which water boils is known as the boiling point of water.
It is another property of water. The boiling point of water is 100 ºC.
56
Chapter 4
At its boiling point, the water in the beaker
starts to become water vapour. Hot water
vapour formed at boiling point (100 ºC) is
known as steam. They are seen as bubbles
in the boiling water. As steam is hot, it rises
to the surface of the water and escapes
into the surrounding air.
te
Lt
d
Mist
The mist observed rising from the surface
of the boiling water is formed due to steam.
on
P
Water may sometimes
contain gases. When the
water is heated, these
gases form bubbles.
These bubbles rise to the
water surface and then
into the air.
A
ls
to
n
E
du
ca
ti
This is why we see bubbles
forming in the water here even
though the temperature of water
has not reached 100 ºC.
yr
ig
h
t
20
23
Particles of liquids and gases during boiling
Particles in water
vapour
C
op
Particles in water
Heat
When a liquid is heated, the liquid particles gain more energy and move faster.
When the particles gain enough energy, they move quickly and freely in all
directions. The particles are also far apart from one another. When this happens,
boiling occurs and water changes from liquid to gas. The process continues until
all of the liquid has boiled off to become gas.
Changing States of Water
57
Solve this!
In the diagram below:
1 Name the processes involved during the changes of states.
2 State the temperature at which each process occurs.
Lt
d
Gas
Process: __________
Temperature: ___ ºC
P
Temperature: ___ ºC
Process: __________
Liquid
k
kboo
or
Worksheet 2
ti
W
Temperature: ___ ºC
on
Solid
te
Process: __________
ca
Where does water disappear to when it is left exposed to the air?
du
Evaporation of water
Think-Pair-Share
ls
to
n
E
Pour some water into a transparent bowl. Use a marker to draw a line to mark the water
level. Leave the bowl exposed to the air overnight.
What do you think will happen to the water level in the bowl the next day?
Particles
in water
Exposed
to air
Particles
in water
vapour
20
23
A
When a bowl of water is left exposed
to the air, the liquid particles at the
water surface gain heat from the
surroundings. The particles gain more
energy and move faster.
C
op
yr
ig
h
t
When the particles have enough energy, they move quickly and freely in all
directions, and escape from the water surface. The particles are now far apart
from each other. When this happens, water changes from liquid to gas. The gas
formed is water vapour.
The process of water at the surface gaining energy and changing to water
vapour is known as evaporation. Evaporation takes place all the time and at
any temperature.
Sometimes we may see mist forming
above hot water, such as a hot spring
or a cup of hot water. This is because
hot water evaporates to form hot water
vapour. Mist is formed from the hot water
vapour.
58
Chapter 4
Mist
Hot water
At hot springs, water is found as a liquid and a gas.
Factors that affect the rate of evaporation
3
Let’s investigate!
te
Materials:
Three transparent bowls
Measuring cylinder
Lt
d
ation.
fects the rate of evapor
af
re
tu
ra
pe
m
te
if
t
ou
Aim: To find
P
Water Marker
Ruler
ca
ti
on
Instructions:
1 Measure and pour 50 ml of water into the three bowls. Use a marker to mark
the water level on the outside of the bowl.
Place each bowl at three different locations with different temperatures.
Under the Sun (Bowl 1)
Classroom at room temperature (Bowl 2)
Indoor in the dark with a lower surrounding temperature than that of Bowl 2
(Bowl 3)
3
Predict what will happen to the water level in each bowl after 30 minutes.
Will the same be observed for all the bowls of water?
_____________________________________________________________
4
Mark the water level in each bowl every 30 minutes. Using a ruler, measure
the height of the water in each bowl.
20
23
A
ls
to
n
E
du
2
ig
h
t
Height
0
minute
Bowl 1
Bowl 2
0
minute
Height
0
minute
Bowl 3
Record your results in a table.
C
op
yr
5
Height
Changing States of Water
59
Questions:
1 What has happened to the water in the different bowls? Which process
causes this to happen?
What is the independent variable of this investigation?
3
Draw a line graph to show how the height of water changes with time for
each bowl.
Height of
water (cm)
te
Bowl 2
Bowl 3
du
ca
ti
on
Height of
water (cm)
P
Bowl 1
Height of
water (cm)
Lt
d
2
Time (min)
E
ls
to
n
The height of the water
in each bowl tells us the
volume of the water.
A greater change in the
height tells us that there
is a greater change in
the volume of water.
After two hours, compare the height of the water across the three bowls.
Which bowl has the lowest height of water?
b
Which bowl has the lowest volume of water?
c
Which bowl lost the most water? Is the temperature of the surroundings
of this bowl high or low?
ig
h
t
a
C
op
yr
4
Time (min)
20
23
A
Draw a line of best fit for each
graph. Are there any points on
your graph that do not follow
the pattern? Do you see any
anomalous results?
Time (min)
Conclusion:
The higher the temperature of the surroundings, the ___________ the volume
of water lost within a given length of time. The volume of water lost over a
period of time can show the rate of evaporation.
So, as the temperature increases, the rate of evaporation ___________.
60
Chapter 4
Lt
d
The temperature of the surroundings of a substance can affect the rate of
evaporation. In places with higher temperatures, the rate of evaporation is
higher. Besides temperature, wind and humidity can also affect the rate of
evaporation.
ca
ti
on
P
te
The more windy the
place is, the higher the
rate of evaporation. Our
clothes dry faster on a
windy day!
In a less humid
environment, there is less water
vapour in the air. The air has space to
hold more water vapour. Water in the
wet clothes can evaporate quickly.
So, the wet clothes can
dry faster.
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
In a very humid
environment, the air is filled with
water vapour. The air cannot contain
any more water vapour so the
water in the wet clothes does not
evaporate easily. The wet clothes
cannot dry well.
The less humid the
place is, the higher the
rate of evaporation.
Changing States of Water
61
What happens when gases are cooled?
Lt
d
Condensation
When a gas is cooled, it can turn into a liquid. This process is known as condensation.
Think-Pair-Share
Lamp
ca
ti
on
P
te
Place a bowl of water covered with plastic film under a light. Place an ice pack on the plastic
film. After some time, what do you observe forming on the side of the plastic film that faces the
water? What has happened?
ls
to
n
E
du
Ice pack
Particles in the
water droplets
20
23
A
Particles in the
water vapour
ig
h
t
Heat from the lamp increases the temperature of the surroundings and
causes the water in the bowl to evaporate quickly into the air underneath the
plastic film.
C
op
yr
When the water vapour touches the cold plastic film, it cools. The gas particles
in the water vapour lose energy to the cold surface and begin to move slower.
When the particles lose enough energy, there is a change in state from gas to
liquid. The water vapour condenses to become water droplets.
62
What do you notice
about the process of
condensation? It is the
opposite of evaporation!
Chapter 4
Watch out!
But it did not rain!
Where did the water
come from?
du
ca
ti
on
P
te
Lt
d
Oh no, I think the
rainwater has seeped
through the window.
ls
to
n
E
Sometimes on cold days, we see water condensing on the side of the window facing the inside
of the house. It is because the window is colder than the surrounding air in the house. There is
water vapour in the air surrounding us. When the water vapour in the house touches the cold
window, it condenses to form water droplets.
Tim spilled some water onto the table and
forgot to wipe it off. A few hours later, the
water on the table disappeared. Using the
particle model, explain why the water on
the table has disappeared.
ig
h
t
20
23
1
A
Solve this!
Cyrus blows air onto a mirror. He
observes some water forming on the
mirror. The air that we breathe out
contains water vapour.
Using the particle model, explain how
water forms on the mirror.
W
C
op
yr
2
k
kboo
or
Worksheet 3
Changing States of Water
63
Crack the case
Water
Lt
d
undergoes
P
where
on
ti
ca
du
Melting point: 0 ºC
Liquid changes
into _________
(water vapour) if
the surrounding
temperature is
higher than 100 ºC
Boiling point : 100 ºC
A
Freezing point: 0 ºC
_________
changes into
_________ if the
surrounding
temperature is
higher than 0 ºC
E
_________
changes into
_________
if the
surrounding
temperature is
lower than 0 ºC
where
ls
to
n
where
Boiling
Melting
Freezing
te
undergoes
20
23
which are
Properties of water
ig
h
t
When a liquid is heated, the liquid particles gain _________ energy and
move _________.
C
op
yr
When the particles gain enough energy, they move _________ and
_________ in all directions.
64
Heat
Chapter 4
Condensation
Lt
d
Evaporation
where
which occurs
_________ changes
into liquid
P
All the time and at
any temperature
ca
du
When _________ particles lose enough
energy, the _________ changes to liquid.
Water vapour condenses to become
water droplets.
20
23
A
ls
to
n
When the particles gain enough
energy, they move _________ and
_________ in all directions, and
escape from the water surface.
When _________ particles lose enough
energy to a cool surface, they begin to
move _________ .
E
Liquid particles at the water
surface gain heat. They have
_________ energy and move
_________.
ti
on
Liquid changes
into _________
(water vapour)
te
where
yr
ig
h
t
Exposed
to air
W
C
op
es fit into her mould without
What can Vera do to ensure that the ice lolli
? Tick (🗸).
overflowing and freezing outside her mould
water can freeze properly.
Lower the freezer temperature so that the
the water can freeze properly.
Increase the freezer temperature so that
so that there is space for the
Fill three quarters of the mould with water
frozen water to expand.
Consolidation worksheet
k
kboo
or
Changing States of Water
65
CHAPTER 5
Solute and Solvent
Lt
d
I am so thirsty!
P
te
We ran out of water.
What should we do?
ca
ti
on
It is so hot today!
Let's rest and get a
sip of water.
This tastes too
salty! I don't think
we can drink this.
ig
h
t
20
23
A
ls
to
n
E
du
Hey! I found
some water
from the sea!
What Will I Learn
C
op
yr
✓ Describe the ability of a solid to dissolve and the ability of a
liquid to act as solvent and state that these are properties
of the solid and liquid.
✓ Use the particle model to describe solutions.
✓ State that dissolving is reversible and investigate how to
separate the solute and solvent in a solution.
✓ Investigate and describe dissolving and relate this process
to mixing.
66
Chapter 5
the
What are
solute and
solvent in
seawater?
Which two
processes can be
used to separate
a solute and a
solvent?
What can
Cyrus and Tim
do to get water
for drinking?
What happens when a solid is added to a liquid?
Retrace our steps
Water
Lt
d
Water
What are the solute
and the solvent in the
following mixtures?
Salt and water
Sand and water
What do you observe when you add salt or sand to water? Why?
te
Sand
P
Salt
ca
ti
on
Salt dissolves in water as salt is soluble in water. In the salt and water
mixture, salt is the solute and water is the solvent.
Sand does not dissolve in water as sand is insoluble in water.
du
What are the characteristics of a solution?
ls
to
n
E
A solute dissolves in a solvent to form a solution. A solution can be
a liquid mixture that contains a dissolved solid. When we add salt to
water, salt dissolves in the water to form a salt solution.
A solution has the following characteristics.
A
A solution is clear and allows light to
pass through it.
C
op
yr
ig
h
t
20
23
A solution is also homogeneous.
This means that the solute and the
solvent are mixed in a way such that
properties like colour and taste are the
same throughout the solution.
We can see
through a salt
solution.
A red food dye solution is clear
and has the same red colour and
taste throughout the solution.
When a solution is left aside to settle, the solute does not float to the
surface or sink to the bottom of the solution. It remains evenly mixed
throughout the solution.
Beaker
Solution
Filter paper
Filtration funnel
Beaker
When we try to filter a solution, no solids
will be collected on the filter paper.
A solute cannot be separated from a
solution by filtering as it is dissolved in
the solvent.
Solute and Solvent
67
P
te
If a solid has
dissolved in a liquid, it will
form a solution. Check
if your mixture has all
the characteristics of
a solution!
Lt
d
Will the brown sugar
dissolve in water?
How do we tell if a
solid has dissolved
in a liquid?
Let’s investigate!
ca
1
ti
on
Do all solids dissolve and do all liquids act as solvents?
in oil.
E
du
dissolve
in water and which solids can
lve
so
dis
n
ca
s
lid
so
ich
wh
t
ou
Aim: To find
ls
to
n
Materials:
Oil
Water
Beakers
Chalk
Sugar
Rice
Flour
A
Salt
Brown sugar
Sand
20
23
Instructions:
1 Plan an experiment to find out which solids can dissolve in water or oil.
Use the following questions to guide you in your plan:
What is the independent variable?
What is the dependent variable?
What are the control variables?
3
Predict which solid(s) will dissolve in water.
yr
ig
h
t
2
C
op
4 Carry out your experiment to see which solid(s) can dissolve in water.
Draw a table and record your results.
68
5
Predict which solid(s) will dissolve in oil.
6
Replace water with oil and repeat your experiment to see which solid(s) can
dissolve in oil. Draw a table and record your results.
Chapter 5
7
Look at the two tables you have drawn earlier. You can summarise your
findings in the table below. Tick (🗸).
Dissolves in water
Dissolves in oil
Lt
d
Sand
Chalk
te
Salt
P
Brown sugar
Sugar
on
Rice
ti
Flour
du
ca
Questions:
1 Can all solids dissolve in water? Do these solids that dissolve in water dissolve
in oil too? __________________________________________________________
What can you say about water and oil as solvents?
Water is a solvent for solids such as _______________. Most solids can dissolve
in _______________ but not _______________.
ls
to
n
E
2
Conclusion:
20
23
A
Solids have different abilities to dissolve in a _______________.
Liquids have different abilities to dissolve a _______________. Not all liquids are
_______________.
ig
h
t
Different solids have different abilities to dissolve in a liquid. Not all solids can
dissolve in water.
C
op
yr
Different liquids have different abilities to dissolve a solid. The same solid that
can dissolve in water may not dissolve in oil. Water has the ability to dissolve
many types of solids. Hence, water can be used as a solvent in different types
of mixtures that we use every day.
The ability of a solid to dissolve is a property of the solid. The ability of a liquid
to act as a solvent is a property of the liquid.
Can you name some examples
of how we use water as a
solvent in our daily lives?
Solute and Solvent
69
What happens to the particles of a solid when it is added to a liquid?
Let’s investigate!
Lt
d
2
te
e
e particles in an insolubl
th
to
s
en
pp
ha
t
ha
w
el
Aim: To mod
n it is added to a liquid.
he
w
lid
so
e
bl
lu
so
a
or
solid
on
P
Instructions:
1 Get into two groups of 9. Group A represents particles in a liquid, while
Group B represents particles in a solid.
Group B
ls
to
n
E
du
ca
ti
Group A
A
In Group A, arrange yourselves in smaller groups
In Group B, stand very close to one another in
of three. Stay in your group as you move around one rows of three. Vibrate at your fixed positions to
another to model how particles behave in a liquid.
model how particles behave in a solid.
Insoluble solid added to liquid
20
23
2
yr
ig
h
t
Model how the particles will behave when an insoluble solid is mixed with
a liquid. Students in Group A would move towards students in Group B.
Students in Group B should remain together without breaking away from
their group.
Group A
C
op
Group A
Group A
70
Chapter 5
Group B represents
particles in an insoluble solid.
3
Soluble solid added to liquid
P
te
Lt
d
Model how the particles will behave when a soluble solid is mixed with a liquid.
Students in Group A should gently pull students in Group B to break up the
group.
Group B
ti
on
Group A
ca
Now, Group B represents particles in a soluble solid.
E
du
Questions:
1 What can we say about the particles in an insoluble solid when it is added to
a liquid?
ls
to
n
________________________________________________________________
Draw a particle model to represent an insoluble solid in a liquid.
Insoluble solid particle
Liquid particle
20
23
A
2
What can we say about the particles in a soluble solid when it is added to
a liquid?
ig
h
t
3
yr
________________________________________________________________
C
op
4
Draw a particle model to represent a soluble solid in a liquid.
Soluble solid particle
Liquid particle
Solute and Solvent
71
Lt
d
An insoluble solid added to a liquid
When an insoluble solid is added to a liquid, the particles of the insoluble solid
remain very closely packed together. The insoluble solid particles do not break
apart.
Liquid particle
te
Particle of an
insoluble solid
du
ca
ti
on
P
After a
while
After a
while
ig
h
t
20
23
Particle of a
soluble solid
A
ls
to
n
E
A soluble solid added to a liquid
When a soluble solid is added to a liquid, the liquid particles pull the soluble
solid particles apart from one another. This breaks the soluble solid apart.
Once the soluble solid is broken apart, they are too small and fine for us to see
them. The soluble solid particles get mixed in between the liquid particles. At
this point, we say that the soluble solid has dissolved in the liquid.
C
op
yr
Liquid particle
In a solution, the fine solid particles fill the spaces between the liquid particles.
When liquid particles move around one another, they may bump or collide with
the solid particles. This may cause the solid particles to move along with the
liquid particles. So, a solution behaves like a liquid and is considered a liquid.
72
Chapter 5
Lt
d
When a solute dissolves in a solvent, there is a mixing of substances. As there
are no new substances formed, dissolving a solute in a solvent is a physical
process.
Solve this!
du
ca
ti
on
P
te
Robert added Substances A and B into two cups of water separately.
Substance B mixed with water
E
Substance A mixed with water
Which substance is soluble in water? Explain your answer.
________________________________________________________________
2
Draw a particle model to represent the mixture containing the substance
stated in 1 .
Label each type of particle.
W
C
op
yr
ig
h
t
20
23
A
ls
to
n
1
k
kboo
or
Worksheet 1
Solute and Solvent
73
How much solid can be dissolved in a liquid?
Think-Pair-Share
Lt
d
What is the greatest amount of salt that we can dissolve in 100 ml of water?
ti
ca
Measuring
cylinder
Transparent
containers
du
Salt
Stirrer
Cold
water
Which of the five types
of scientific enquiry can
we use to carry out the
investigation? What
equipment do we need?
E
Materials:
Hot water
Marker
Teaspoon
on
olve in 100 ml of water.
ss
di
n
ca
lt
sa
h
uc
m
w
ho
Aim: To find out
te
Let’s investigate!
P
3
Add one teaspoon of salt into the water and observe.
What did you observe? Did the salt dissolve in water?
______________________________________________________________
A
2
ls
to
n
Instructions:
1 Put 100 ml of cold water in a container and mark the water level with a marker.
20
23
Stir the mixture using a stirrer and observe.
a Did the salt dissolve in water? _______________
b How do you know when all the salt has completely dissolved?
____________________________________________________________
c How many times do you need to stir the mixture to dissolve the salt? ____________________________________________________________
ig
h
t
3
yr
Add another teaspoon of salt into the water and stir.
5 Repeat Step 4 with one teaspoon of salt at a time until
no more salt can be dissolved. How many teaspoons of
salt did you add until no more salt can be dissolved?
Record in the table on the next page.
C
op
4
6
74
Observe and note the water level in the container.
Chapter 5
How do we
know when no
more salt can
be dissolved?
Repeat Steps 1 to 6 but replace the cold water with 100 ml of hot water.
How many teaspoons of salt did you add until no more salt can be
dissolved? Record in the table below.
7
Number of teaspoons of salt
Lt
d
Temperature of water
Cold water
te
Hot water
on
P
Question:
Compare the water level in Step 1 and Step 6. Describe the change in the water
level. Explain the change in the water level.
du
ca
ti
Conclusion:
Stirring helps the salt to dissolve ( faster/ slower ) in water.
( More / Less ) salt can dissolve in 100 ml of hot water than in 100 ml of cold water.
ls
to
n
E
When no more salt can be dissolved in a given amount of water, the solution is
saturated.
A saturated solution contains the maximum amount of solute dissolved in a
solvent at a given temperature.
20
23
A saturated salt solution
has the maximum number
of salt particles mixed
evenly between water
particles.
A
Water particle
Salt particle
Adding
more
salt
If more salt is added to the
saturated salt solution, the
salt added will not be able
to dissolve. The particles in
the undissolved salt do not
break apart.
C
op
yr
ig
h
t
A solid can dissolve faster if we stir the mixture
Salt does not dissolve quickly in cold water. To make salt dissolve faster, we
need to stir the mixture.
Stirring helps to break up any big lumps of salt into finer grains. This increases
the surface area of the salt exposed to water. It also helps to spread the salt
evenly throughout the water.
Salt in cold water
Salt in cold water
after stirring
Solute and Solvent
75
If we do not stir the
mixture, will the salt
dissolve?
Even if we do not stir the mixture, the salt will still dissolve
in water. However, it will take a longer time for the process
to complete. The ability of salt to dissolve in water is a
property of salt. It does not depend on stirring.
Lt
d
Watch out!
P
te
A solid can dissolve faster at higher temperatures
Think-Pair-Share
Add the same amount of salt to
each beaker of water.
ti
2
on
Prepare two beakers containing the
same volume of water at different
temperatures.
du
ca
1
ls
to
n
E
Which beaker of water is able to dissolve the salt first?
Salt dissolves faster in the water at a higher temperature. The higher the
temperature, the faster the solute dissolves.
In Let's investigate 3, more
salt can be dissolved in 100 ml
of hot water than in 100 ml of
cold water.
ig
h
t
20
23
A
More solids can dissolve in a solvent at higher temperatures
When the temperature is higher, more solute can dissolve in the same amount
of solvent.
Solve this!
W
C
op
yr
Vera added some food dye powder in 500 ml of cold water. After
she stirred the mixture, the powder dissolved. Then, Vera added
more food dye powder to the water. She observed that some food
dye powder settled to the bottom of the container. It did not
dissolve even though Vera continued to stir the mixture.
1 What has happened to the mixture?
2 What should Vera do to the mixture to dissolve the remaining
food dye powder that has settled to the bottom of the container?
76
Chapter 5
k
kboo
or
Worksheet 2
How can we separate the solute and the solvent in a solution?
Lt
d
Dissolving is a physical process. It is reversible and we can obtain the solute
even after it has dissolved in a solvent. Unlike physical processes, chemical
reactions or processes are irreversible.
Think-Pair-Share
Pour some saturated salt solution into a shallow dish.
Place it near the window for a week. Check the dish after a week.
te
P
on
ti
Questions:
What has happened to all the water?
What is left in the dish?
How can you change the set-up to collect the water as well?
Saturated salt
solution
Retrace our steps
What factors affect
the rate of water
evaporation?
20
23
A
ls
to
n
E
du
ca
When a salt solution is left exposed to the air, the water in
the solution can evaporate and become water vapour.
The salt in the solution does not evaporate and is left
behind in the dish. The size and appearance of the salt
grains left behind depend on how quickly or slowly the
water in the solution evaporates. If the evaporation of
water occurs very slowly, large salt crystals may be formed.
Salt solution
Cold
surface
Salt crystals
ig
h
t
We can collect the water that has evaporated from the
solution by condensing the water vapour on a cold surface.
Solve this!
op
yr
Sophia accidentally spilled some sugar into a bowl
of water.
C
What can she do to get the sugar out of the water?
Clues
Crystal – A solidified substance with flat faces and sharp angles
Solute and Solvent
77
Using the particle model to explain how solutes and solvents are separated
te
Lt
d
Now that we have learnt
how to separate the
solute and the solvent,
let's see what happens
to the particles in a
particle model!
P
Think-Pair-Share
ti
on
What happens to the particles when the salt solution is left to evaporate?
Imagine that you and your classmates are particles in a salt solution.
Model the movement of salt and water particles in the solution during the
evaporation process.
Water particle
Salt particle
20
23
A
ls
to
n
E
du
ca
Use the following questions to help you.
What happens to the water particles in the solution?
What happens to the salt particles in the solution?
C
op
yr
ig
h
t
During evaporation, the liquid water particles at the surface
of the salt solution gain energy from the surroundings and
move faster.
78
Chapter 5
When the liquid water particles gain enough energy, they
become gas particles. They can move very quickly and are
far apart from one another. The gas particles are the water
vapour that escapes into the air.
The solid salt particles remain in the
solution. When all the liquid water
particles have become gas particles in
water vapour, the solid salt particles are
left behind.
Science in context
We use the evaporation process to help us
harvest sea salt from seawater.
We can create shallow salt evaporation
ponds and pump saltwater into them. After
all the water has evaporated from these
ponds, we can collect the salt left behind.
te
Lt
d
This is a salt
evaporation pond!
du
ca
ti
on
P
Watch the following video to
see how sea salt is harvested!
ls
to
n
E
We can use a solar still to obtain water from
the sea. In a solar still, the heat from the Sun
causes water in the seawater to evaporate.
Water vapour condenses on the cooler
surface inside the dome.
Water vapour
condenses on the dome
to form water droplets
ig
h
t
Dome lets in
sunlight and
traps heat
20
23
A
The surface is shaped in a way so that water
that has condensed will flow to the sides of
the dome and get collected.
We cannot drink seawater as it
contains a lot of salt! We need
to process seawater first before
we can drink it.
Seawater
Solar still
Water is collected
here
W
C
op
yr
Water droplets
flow to the side
k
kboo
or
Worksheet 3
Solute and Solvent
79
Crack the case
Solvent
to dissolve
a
Solute
te
Ability to act as a
solvent
Lt
d
Ability to dissolve
ti
on
Liquid
has
in a
P
Solid
has
ca
involved in a
process called
ls
to
n
Temperature is
____________
E
occurs faster
when
du
____________ the mixture
is
to form
Solutions
can become
20
23
A
have characteristics
including
Dissolving
No ____________ will be
collected on the filter
paper if we filter a solution
C
op
yr
ig
h
t
Allows ____________ to
pass through
80
Chapter 5
Homogeneous
Solute does
not float to the
surface or sink
f
to the bottom o
a solution when
ft
the solution is le
aside to settle
Lt
d
Can be separated into ____________ and ____________
P
te
through processes
including
Condensation
ca
ti
on
Evaporation
Reversible
E
du
The solution contains the ____________
amount of solute dissolved in a solvent
at a given temperature
ls
to
n
when
Saturated solutions
20
23
A
if we add more solids
The added solids remain
____________ in the solvent
even after stirring
ig
h
t
drinking? Tick (🗸).
What can Cyrus and Tim do to get water for
l.
Collect and drink the seawater using a bow
l for drinking.
When it rains, collect the rainwater in a bow
separate the water from the
eave the seawater exposed to the air to
L
salt to obtain water for drinking.
Consolidation worksheet
W
C
op
yr
r to remove the salt and
oil the seawater. Then, use a T-shirt as filte
B
collect the water in a bowl for drinking.
w water vapour to condense
Boil the seawater. Then, hold the lid to allo
obtain water for drinking.
and collect the water droplets in a bowl to
k
kboo
or
Solute and Solvent
81
CHAPTER 6
Forces
te
Lt
d
The children are planning to
give Vera a birthday
surprise. They are planning
to drop Vera's gift
from a height. They want the
gift to fall slowly in
the air and land in front of Ve
ra when she passes
the building.
What can I use?
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
on
P
I am going to drop
the stuffed toy
from here. Here it
comes!
C
op
yr
What Will I Learn
✓ Identify different types of forces.
✓ Describe that an object may have multiple forces acting upon it.
✓ Draw force diagrams to show the name and direction of each force acting on an object.
What forces act
on the stuffed
toy as it falls in
the air?
82
Chapter 6
Which force is needed in great
amount to help the stuffed toy
fall slowly in the air?
Why do objects fall to the ground when we drop them in the air?
Think-Pair-Share
Retrace our steps
Lt
d
Drop a plastic ball and a tennis ball from the
same height.
What happens to the balls when you let go of them?
What causes the balls to fall? Which ball reaches
the ground first?
P
te
What is gravity?
on
Gravity
du
ca
ti
A ball falls towards the ground when we release it from a height.
Gravity pulls the ball towards the centre of the Earth. Gravity affects
how fast it takes for an object to reach the ground.
Gravity
20
23
Gravity
The tennis ball is heavier. Why did
it not reach the ground first?
ls
to
n
Tennis ball
A
Plastic ball
E
Watch out!
On Earth, the gravity acting on any object
is the same. When objects are dropped
from the same height, they should reach
the ground at the same time. So, the
tennis ball and the plastic ball will reach
the ground at the same time.
ig
h
t
What are the forces acting on an object at rest on a surface?
If gravity always pulls an object
towards the centre of the Earth, why
does the book not fall through the
table and onto the ground?
C
op
yr
Normal force
Forces
83
An object resting on a surface is in contact with the surface. The surface exerts
a normal force on the object. The normal force acting on the object is always
at a right angle to the surface it is in contact with.
Normal force
Lt
d
The arrow indicates the
direction of a force. The length
of the arrow indicates the size
of a force. The label of the
arrow indicates the type of
force acting on
the object.
on
P
te
We use a force
diagram to represent
forces acting on
an object.
ca
ti
Gravity
du
A force diagram showing the forces
acting on a box resting on a table
ls
to
n
E
For an object resting on a flat, horizontal surface, the normal force acts in the
opposite direction of gravity. It balances the gravity acting on the object. We
say that the forces acting on the object are equal and balanced. This is why
the object does not fall through the table and onto the ground. It remains at
rest on the table surface.
A
We can label the arrow
with the size of the force if we
have the information. The size
of each force here is 25 N.
Normal force
ig
h
t
20
23
25 N
C
op
yr
25 N
84
Chapter 6
We can also put
markings on the
arrow to indicate the
size of the force.
Gravity
Other types of forces diagrams
Normal force
The forces acting on the
ball resting on the floor are
balanced. So, the ball does
not fall through the floor.
Gravity
A force diagram showing the forces
acting on a ball resting on the floor
Think-Pair-Share
Will normal force still act on the ball when it is rolling
down the slope? Discuss with your classmates.
Lt
d
What is the direction of the normal force acting on
the ball? Draw an arrow on the diagram to represent
the normal force.
te
Gravity
P
Solve this!
ti
k
kboo
or
Worksheet 1
E
What force causes an object at rest to start moving?
W
du
ca
Draw a force diagram to indicate the forces acting
on the ball.
on
A ball is resting on a structure shown on the right.
Retrace our steps
ls
to
n
Applied force
A
When we apply a force to a ball at rest, the forces
acting on the ball become unbalanced. The effect of
the unbalanced forces causes the ball to move in the
direction of the applied force.
What will happen if
we apply a force to
a ball resting on a
surface?
Friction
Let’s investigate!
ig
h
t
1
20
23
What forces can cause a moving object to slow down?
yr
distance travelled by
e
th
s
ct
fe
af
n
io
ct
fri
of
e amount
Aim: To find out how th
ct to stop moving.
je
ob
g
in
ov
m
e
th
r
fo
n
take
an object and the time
C
op
Retrace our steps
Materials:
Wooden board
Bottle cap
Stack of books
Stopwatch
Ruler
Carpeted rug
Smooth floor
What is friction?
Which type of
surface generates
the most amount of
friction?
Forces
85
Instructions:
1 Set up your materials according to the diagram below.
Stop the
stopwatch
P
Books
Start the
stopwatch
te
Wooden
board
Lt
d
Mark a start line on the wooden board.
This is where the bottle cap will be released from.
on
Smooth floor
Allow the bottle cap to slide down from the start line onto a smooth floor.
ca
2
ti
Distance travelled
Start the stopwatch when the bottle cap touches the floor. Stop the
stopwatch when the bottle cap comes to a stop.
4 Use a ruler to measure the distance travelled by the bottle cap on the floor.
5 Replace the smooth floor with a carpeted rug. Repeat Steps 1 to 4.
6 Draw a table to record your results.
yr
ig
h
t
20
23
A
ls
to
n
E
du
3
C
op
Questions:
1 Which surface has a rough texture? __________
2 Which surface allows the bottle cap to move a greater distance?
______________________________________________________________
3
86
On which surface does the bottle cap take a longer time to come to a stop?
______________________________________________________________
Chapter 6
Conclusion:
A ________ surface generates a ________ amount of friction. A moving object
Lt
d
comes to a stop ________ when travelling over a ________ surface. So, the
te
distance travelled by the object over a ________ surface is __________.
Friction
Friction
Carpeted rug
du
Smooth floor
ca
ti
on
P
Friction is a force that opposes motion. The amount of friction generated
depends on the type of surface that the object is in contact with.
ls
to
n
E
A carpeted rug has a rough surface. The sliding bottle cap experiences
a greater amount of friction when it slides over the carpeted rug.
A rough surface generates a greater amount of friction
than a smooth surface. So, a rough surface will cause the
object travelling on it to slow down and come to a stop
faster than a smooth surface. As a result, the moving
object travels a shorter distance on a rough surface.
Retrace our steps
Solve this!
20
23
A
What can we use
to help us reduce
friction?
A
B
C
Draw a force diagram to show all the forces acting on the sliding box.
The box stopped at B. If the floor is wet, predict the position (A, B or C) that the
box will stop at. Explain your answer.
W
C
op
yr
ig
h
t
The diagram below shows a box sliding across a surface towards the right.
k
kboo
or
Worksheet 2
Forces
87
Air resistance
2
Let’s investigate!
Sheet of
paper
te
Ball of
paper
Stopwatch
P
Materials:
Sheets of paper of the same size Lt
d
s the
area of an object affect
ce
rfa
su
e
th
w
ho
t
ou
d
Aim: To fin
e ground.
time it takes to reach th
ls
to
n
E
du
ca
ti
on
Instructions:
1 Scrunch up one sheet of paper into a ball.
2 Drop the ball of paper and a flat sheet of paper
from the same height at the same time. Observe
which object reaches the ground first.
3 Now, measure the time taken for each object to
Stopwatch
reach the ground. Your classmate should start the stopwatch when you drop each object.
4 First, drop the ball of paper. Next, drop the flat
sheet of paper from the same height. Your classmate should
stop the stopwatch when each object touches the ground.
ig
h
t
20
23
A
Questions:
1 Which object reached the ground first? ________________
2 Which object took a longer time to reach the ground? ___________________
3 What are the forces acting on the objects as they fall? ___________________
4 Which object has a greater surface area in contact with the air as it falls?
________________________
C
op
yr
onclusion:
C
An object with a __________ surface area takes a longer time to reach the ground.
Air resistance will __________ down the fall of an object in the air.
88
Chapter 6
An object moving through air is in contact with the
gas particles in the air. There is friction between the
surface of the object and the gas particles.
Retrace our steps
What is air resistance?
What effect does it have
on an object moving
through the air?
te
Lt
d
This form of friction is known as air resistance.
Air resistance is an opposing force that slows down
the fall of an object in the air.
The sheet of paper falls
slower through the air than
the ball of paper.
Sheet of
paper
Gravity
Air
resistance
Ball of paper
Gravity
Air
resistance
20
23
A
ls
to
n
E
du
ca
ti
on
P
Parachutes have a large surface
area to slow down the fall and allow
the parachutist to land safely.
ig
h
t
A sheet of paper has a larger surface area than a ball of paper. So, the sheet of
paper collides with more air particles and experiences a greater amount of air
resistance than the ball of paper.
yr
The amount of air resistance acting on an object depends on the surface
area of the object. An object with a greater surface area will collide with
more air particles. So, it experiences a greater amount of air resistance and
moves slower in the air.
C
op
High-speed trains and rockets have
pointed ends and less surface area
in contact with air. This reduces air
resistance so that they can travel faster.
Yay! I am winning!
It is so difficult to go
fast with this car!
Forces
89
Water resistance
Lt
d
Similar to objects moving through air, objects moving through water
experience friction too. This form of friction is known as water resistance. It is
also an opposing force. It is friction between the surface of the object and the
water particles.
on
P
te
Similar to air resistance, an object with a large surface area in contact with
water experiences a greater amount of water resistance. It is harder to
move such an object in the water as it requires a greater amount of force to
overcome the water resistance.
ti
Let’s investigate!
3
E
du
ca
the amount of force
s
ct
fe
af
nt
fro
's
at
bo
e
Aim: To find out if th
move through water.
needed for the boat to
ls
to
n
Materials:
Modelling clay
String
Forcemeter
ig
h
t
20
23
A
Instructions:
1 Shape two balls of modelling clay into boats. Make sure they have flat
bottoms so that they can float in water.
2 Then, shape the front of each boat according to the diagram below.
Boat with a pointed front
Tie strings to one end of each
boat.
C
op
yr
3
90
Chapter 6
Boat with a flat front
4
Place each boat in water. Drag the
boat slowly across the water using a
forcemeter.
Lt
d
Question:
Which boat is harder for you to drag through water? Which boat requires a
greater amount of force to move through water?
______________________________________________________________
on
P
te
Conclusion:
A boat with a ___________ front requires a smaller amount of force to move
through water.
A boat with a ___________ front requires a greater amount of force to move
through water.
Water resistance
A
Pointed front of
the ship in contact
with water
ls
to
n
E
du
We are nearing
the shore!
ca
ti
When the ship is moving through water, some parts of the ship are above
water and some parts are in the water. The shape of the front of the ship in
contact with water affects how fast it can move through water.
We are nearing
the dock!
C
op
yr
ig
h
t
20
23
A ship with a narrow or pointed front has a smaller surface area in contact
with water. This type of ship experiences less water resistance when moving
through water. So, it moves faster in water.
Flat front of the ship
in contact with water
Water resistance
A ship with a flat front has a greater surface area in contact with water. This
type of ship experiences a greater amount of water resistance when moving
through water. So, it moves slower in water.
Forces
91
Solve this!
Lt
d
Sports cars are designed to move fast.
The sports car experiences friction between the wheels and the ground
when it is moving. It also experiences another opposing force while it is
moving. What is this force?
2 Refer to the picture of the sports car. Describe the shape of the front part of
the sports car. Using particles, explain how the shape of its front helps the
car to move fast.
on
P
te
1
ti
Think-Pair-Share
20
23
A
ls
to
n
E
du
ca
What are the forces acting on the children at the playground? Discuss.
Draw force diagrams to show the forces acting on each child.
What are the forces acting on an object in water?
Think-Pair-Share
ig
h
t
What are the forces acting on an object resting on the
surface of water? Discuss.
C
op
yr
Push an inflated balloon into the water. Did you feel any
force resisting your push? Push the balloon down so that
the entire balloon is underwater. Was it easy to do so?
92
Chapter 6
Upthrust
du
ca
ti
on
P
te
Lt
d
When we try to push an object into water, we would feel a force pushing the
object up. This upward force is caused by upthrust exerted by the water on
the balloon.
It is difficult for us to push an inflated balloon completely into the water
because upthrust increases as we try to push more of the balloon into
the water.
ls
to
n
E
Upthrust
Upthrust
A
Whether an object floats or sinks depends on the amount of upthrust and the
gravity acting on it. Upthrust acts in the opposite direction of gravity.
At the surface of water, the amount
of upthrust acting on the object is
the same as the amount of gravity
acting on the object.
Gravity
Gravity
Upthrust
Upthrust
Upthrust
C
op
yr
ig
h
t
20
23
When the upthrust acting on an object
in water is greater than the gravity
acting on the object, the object rises
to the surface of the water.
Forces acting on the balloon are unbalanced.
The balloon rises and floats to the surface of
the water.
Forces acting on the balloon are balanced.
The balloon remains at rest and floats on the
surface of the water.
Forces
93
Metal ball
Forces acting on the metal ball are
unbalanced. The metal ball sinks in water.
te
Upthrust
Gravity
P
Solve this!
Lt
d
When the amount of upthrust acting on an object
in water is less than the gravity acting on the
object, the object sinks.
ls
to
n
Science in context
W
Worksheet 3
20
23
A
Air
resistance
Upward force
due to the push
generated from
the burning of fuel
The amount of fuel in one
Falcon 9 rocket is about
147,000 kg! What are the
effects on the environment if so
much fuel is burnt during a
rocket launch?
C
op
yr
ig
h
t
This rocket is
called Falcon 9!
Watch the
launch of
Falcon 9 in
this video.
k
kboo
or
E
du
ca
ti
on
Draw a force diagram to
show the forces acting on the
rubber duck.
94
Chapter 6
Gravity
I am an aerospace
engineer. I need to
understand the different
forces acting on a rocket
during a launch so that
I can build rockets that
require less fuel
to launch.
It is not easy
to launch a rocket! A rocket
needs to burn enough
fuel to push itself upward
against the downward
forces acting on it.
Crack the case
Forces
Types of forces
te
P
An object in water
will experience
________ exerted
by the water.
ti
ca
ls
to
n
An object at rest on a
surface will experience a
________ force exerted
by the surface.
20
23
A
_____________ is a
force that ________
the motion of object
in water.
What can Tim and Cyrus do to help the stuffed
toy fall slowly in the air? Tick (🗸).
ig
h
t
Scrunched-up ball
of paper
ecure it to a scrunched-up ball of paper
S
using strings.
Plastic bag
yr
Secure it to a plastic bag using strings.
Secure it to a piece of cloth using strings.
Cloth
W
op
C
Any object on Earth
will have ________
acting on it.
E
have different forms
_____________ is a
force that ________
the motion of object
in air.
on
________ is a force that
opposes the motion of an
object. It is generated when
two objects move against
each other. It is larger when
the surfaces of the objects
are _____________.
du
An ________
force causes the
forces acting on
an object at rest
to be unbalanced.
This can cause
the object to
move.
Lt
d
Forces acting on an object can be
represented by a force diagram.
k
kboo
or
Consolidation worksheet
Forces
95
CHAPTER 7
Tim is walking to school. He
has dropped his steel name
tag into a drain by
accident. He needs to retrie
ve his name tag but the dra
in cover is sealed.
What should Tim do to get his
name tag out of the drain qu
ickly?
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
on
P
te
Oh no! My teacher will
not be very happy with
me if I do not have my
name tag with me!
Lt
d
Magnets
C
op
What Will I Learn
Identify the differences between a magnet and a
magnetic material.
Describe how forces act over a distance between magnets,
and between a magnet and a magnetic material.
State that magnets can have different magnetic strengths.
96
Chapter 7
agnetic
Is steel a m
gnetic
or non-ma
material?
What happens to a
magnetic material
when a magnet is
brought near it?
What are the differences between a magnet and a
magnetic material?
Retrace our steps
Lt
d
A magnet has poles
What is a magnet?
How do magnets
interact with each
other?
ca
ti
on
P
te
Every magnet has a north pole and a south pole.
The opposite poles of magnets can exert forces
of attraction on each other over a distance.
du
Opposite poles of magnets attract.
I wish I could
exert forces on my food
from a distance.
ig
h
t
20
23
A
ls
to
n
E
Why are magnets able
to exert forces without
touching each other?
C
op
yr
The same poles of magnets can exert forces of repulsion on each
other over a distance.
Same poles of magnets repel.
Magnets
97
Lt
d
A magnet has magnetic fields
All magnets exert a magnetic force around them. The magnetic field is an area
surrounding a magnet where the force of the magnet can be experienced.
Magnetic fields are invisible to our eyes. We cannot see them but we can
observe their effects.
du
Magnetic field lines always start from the north
pole and end at the south pole of the magnet.
ca
ti
on
P
te
We can use magnetic
field lines to represent the
magnetic field around a
magnet. This is a useful way of
helping us to picture the
magnetic field!
20
23
A
ls
to
n
E
A magnet placed within the magnetic field of another magnet can experience
forces of attraction or repulsion.
These are the magnetic field lines between
magnets with opposite poles facing each
other. These magnets attract each other.
These are the magnetic field lines between
magnets with the same poles facing each
other. These magnets repel each other.
C
op
yr
ig
h
t
Magnetic fields can pass through thin materials such as paper. When a sheet
of paper is placed between two magnets, magnets can still attract or repel
each other.
98
Chapter 7
A sheet of paper
A sheet of paper
Watch out!
Wow! My magnets
can stick onto
each other!
Lt
d
Magnets are not sticky!
Look! This magnet can still attract
the other magnet even with a
sheet of paper between them!
It is the force of attraction that
pulls them together.
te
Sheet
of paper
du
ca
ti
on
P
As a magnet moves away from the magnetic field of another magnet, the
force between the two magnets becomes weaker. At a certain distance, the
magnetic force becomes so weak that the magnets can no longer attract or
repel each other. We call this the maximum distance of the magnetic field of
the magnet. So, when the magnets are too far apart, the magnets will not exert
any force on each other.
ls
to
n
A
20
23
Science in context
E
Why is my magnet
not able to attract the
ring magnet behind
Momo?
What should Coco do to attract the ring magnet on Momo?
ig
h
t
Engineers use their knowledge of magnetic interactions to develop the
magnetic levitation train.
The magnetic levitation
train moves in the air so
there is no friction between
the train and the surface
of the train tracks. It moves
much faster than a
normal train!
C
op
yr
Watch this video
to find out how the
train moves using
magnets.
Magnetic levitation train
The train uses the repulsion force of
magnets to levitate. It also uses the attraction
force of magnets to push the train forward.
Clues
Levitate – To rise and float in the air, overcoming gravity without any support
Magnets
99
A magnet can attract magnetic materials
Think-Pair-Share
What is a
magnetic
material?
P
te
Predict which of the following are magnetic materials.
Explain your predictions.
Use a bar magnet to test if your predictions are true.
Lt
d
Retrace our steps
ti
on
What is similar among the magnetic materials?
Were there items made of metal that are not attracted to the bar magnet?
ls
to
n
E
du
ca
Magnetic materials generally contain iron. When a magnetic material is placed
near a magnet, it will be attracted to it. A magnet has a magnetic field. When
placed within the magnetic field, the magnetic material can experience the
attractive force of the magnet. This is how a magnet can exert a force on the
magnetic material over a distance.
20
23
A
This paper clip is made of steel.
What happens to the paper clip
when you move your magnet?
Using your knowledge of magnet
and its magnetic field, discuss
and explain your observations.
ig
h
t
Iron filings are very fine pieces of iron metal. They will get attracted to a
magnet when placed within the magnetic field of the magnet. We can use iron
filings to help us see the magnetic field of the magnet.
yr
Think-Pair-Share
C
op
Place a piece of paper on top of a bar
magnet. Sprinkle some iron filings on
the paper. What do you observe? Draw.
100
Chapter 7
P
te
Lt
d
There are more iron filings near the poles of the
magnets. As we move away from the magnet,
the amount of iron filings decreases. This shows
that the magnetic force is stronger near the
magnet, but gets weaker as we move further
away. At the maximum distance, the magnetic
force becomes so weak that it can no longer
attract any magnetic materials.
Watch out!
on
Remember that
I said that magnets are not
sticky? Look! The paper
clip can be attracted to the
magnet even when I put a
sheet of paper between
them!
du
ca
ti
I can stick the
paper clip to my
magnet!
Sheet of paper
ls
to
n
Bar magnet
E
Bar magnet
Paper clip
made of steel
Paper clip
made of steel
20
23
A
The magnetic field of a magnet can pass through the sheet of paper. The force of attraction
exerted by the magnet can pull the magnetic material towards the magnet even when a
sheet of paper is placed between them.
Can we tell if an object attracted to a magnet is a magnet or a
magnetic material?
My toy is
attracted to my bar
magnet. Does my toy
contain a magnet or
magnetic material?
How do I tell?
Place your toy near
the other pole of the
bar magnet.
C
op
yr
ig
h
t
Think-Pair-Share
What will Tim observe if his toy contains a magnet?
What will Tim observe if his toy contains a magnetic material?
Magnets
101
We cannot tell whether an object is a magnet or a magnetic material
by observing the effect of forces of attraction between the magnet and
the object.
Lt
d
This is because a magnet can attract another magnet when their opposite
poles are facing each other. A magnet can also attract magnetic objects.
te
P
ca
A magnet repels the same pole of another magnet.
du
Solve this!
A coin made of steel is placed near a magnet.
Draw an arrow to show what will happen to the coin.
E
1
ti
on
If the object repels another magnet, the object is a magnet.
Therefore, we
can only tell that an
object is a magnet
if the object is able
to repel another
magnet.
A
ls
to
n
Complete the sentences.
The magnet has a _____________ around it. The coin is made of ___________
material. When the coin is placed near the magnet, a _______________ will
be acting on the coin, causing the coin to be _____________ to the magnet.
Another object is placed near a magnet. How do we tell if this object is also
a magnet? ______________________________________________________
20
23
2
ig
h
t
What happens to a magnetic material when it is near a magnet?
C
op
yr
A magnetic material becomes a temporary magnet when it is near a magnet
or in contact with a magnet.
A temporary magnet has the properties of a magnet. Just like a magnet, it has
a north pole and a south pole.
The side of the temporary magnet that is near or in contact with the magnet
will have a pole opposite to the pole of the magnet.
When the iron nail becomes a temporary
magnet, the side of the iron nail in contact
with the bar magnet becomes the north pole
of the temporary magnet.
102
Chapter 7
Let’s investigate!
1
Bar magnets
Bring a bar magnet near the iron nail.
ca
2
ti
on
Instructions:
1 Place the iron nail and the paper clip near each other.
Did anything happen? _________________________
te
Paper clip made of steel P
Materials:
Iron nail Lt
d
rary magnet by placing
po
m
te
a
to
in
ct
je
ob
tic
Aim: To change a magne
netic object.
a magnet near the mag
Bring another bar magnet near the other end of the iron nail. Position each
pole of the bar magnet according to the diagrams shown below.
E
3
du
What did you observe? ________________________
We can tell if an
ls
to
n
What did you observe? ____________ object is a magnet
by observing if
________________________________ there
are forces of
repulsion.
Bring the set-up in Step 2 near a paper clip.
What happens to the paper clip?
________________________________________________________________
ig
h
t
4
20
23
A
What did you observe? ____________
________________________________
C
op
yr
Questions:
1 What do you think happened to the iron nail in the experiment? Label the
magnetic poles of the temporary iron nail magnet in the diagram below.
2
Explain how your observations in Step 3 tell you that the iron nail has
become a temporary magnet.
________________________________________________________________
________________________________________________________________
Magnets
103
S
N
Groups of particles inside a magnetic material
on
Groups of particles inside a magnet
te
N
P
S
Lt
d
How a magnetic object becomes a temporary magnet
To understand how a magnetic object becomes a temporary magnet,
we need to look at the particles inside a magnet and a magnetic material.
du
ca
ti
In a magnet, groups of particles are aligned and face the same direction.
In a magnetic material, groups of particles are not facing the same direction.
They are not aligned, unlike those in a magnet.
Iron nail
A
ls
to
n
E
The groups of
particles act like mini
magnets in the nail!
20
23
When a magnetic material is near a magnet, the groups of particles in
the magnetic material become aligned and face the same direction. The
magnetic material becomes a temporary magnet.
N
C
op
yr
ig
h
t
A temporary magnet can
cause other magnetic
materials near it or in
contact with it to become
temporary magnets too!
S
N
S
N
Paper clip made of steel
S
W
The paper clips which are attracted to the temporary iron nail magnet become temporary
magnets. Each paper clip has opposite poles on its two ends when it becomes a temporary magnet.
104
Chapter 7
k
kboo
or
Worksheet 1
2
Let’s investigate!
Paper clip made of steel Bar magnet
te
Materials:
Iron nail Lt
d
rary magnet by stroking
po
m
te
a
to
in
ct
je
ob
tic
Aim: To change a magne
ing a magnet.
the magnetic object us
ca
ti
on
P
Instructions:
1 Use a bar magnet to stroke an iron nail 20 times in the same direction as
shown below.
du
Bar magnet
Iron nail
Repeat Step 1
if your iron nail
cannot attract the
paper clip.
Bring the iron nail near a paper clip. Did the iron nail
attract the paper clip? ________________________
3
Bring the iron nail near the poles of the bar magnet as shown below.
ls
to
n
E
2
20
23
A
What did you observe? ____________
________________________________
What did you observe? _____________
_________________________________
yr
ig
h
t
Questions:
1 Describe the observation that tells you that the iron nail has become a
temporary magnet.
________________________________________________________________
Draw the iron nail and label its poles.
C
op
2
Magnets
105
Lt
d
A magnetic material can become a temporary magnet when it is stroked
many times continuously in the same direction along its length by a magnet.
After stroking many times, the groups of particles in the magnetic material
become aligned to face the same direction. The end of the magnetic material
where the stroke finishes will have a magnetic pole opposite to the pole of the
magnet in contact with the magnetic material.
After stroking many times
te
Before stroking
du
ca
ti
on
P
This end will
have a magnetic pole
opposite to the pole
of the magnet that is
touching the nail!
N
E
S
ls
to
n
Watch out!
A
After a magnetic material becomes a temporary magnet, the magnetic material behaves like a
magnet. However, this does not mean that the properties of a magnet were transferred to the
magnetic material. We use the magnet to align the groups of particles in the magnetic material
to face the same direction. When the groups of particles face the same direction, the properties
of the magnetic material change and it starts to behave like a magnet.
20
23
What can cause temporary magnets to lose their
magnetic properties?
ig
h
t
Temporary magnets can lose their magnetic properties.
W
C
op
yr
Temporary magnets can lose
their magnetic properties if we
drop them many times on a
hard surface.
Some electrical
equipment can also cause
temporary magnets
to lose their magnetic
properties.
106
Chapter 7
k
kboo
or
Worksheet 2
Do all magnets have the same magnetic strength?
Let’s investigate!
Iron filings
ca
ti
Materials:
Magnets of different sizes, labelled A, B, C and D on
P
magnetic strength.
e
m
sa
e
th
ve
ha
ts
ne
Aim: To find out if all mag
te
3
Lt
d
Magnetic strength is the ability of a magnet to exert forces on other magnets
or magnetic materials near it.
Shape
Size
ls
to
n
A
E
Magnet
du
Instructions:
1 Observe the shapes and sizes of the magnets. Record your observations below.
B
C
A
D
Predict which magnet is the strongest.
My prediction: _________________________
3
Bring each magnet near some iron filings. Observe.
Which magnet attracted the most amount of iron filings?
Which magnet attracted the least amount of iron filings?
ig
h
t
20
23
2
C
op
yr
Questions:
1 Which magnet is the strongest? Why do you say so?
2 Which magnet is the weakest? Why do you say so?
3 Does the size of a magnet affect its strength? Why or why not?
Conclusion:
Different magnets have ________ magnetic strengths.
The strength of a magnet ( is / is not ) related to the size of the magnet.
Magnets
107
Lt
d
Different magnets have different strengths. A stronger magnet can attract
more iron filings than a weaker magnet. The strongest magnet is called a
neodymium magnet. It is a magnet made of neodymium, iron and boron.
We can find neodymium magnets in our mobile phones, televisions, laptops
or computers.
P
te
Will the strength of a magnet affect the maximum distance that it can exert its
magnetic force over?
Let’s investigate!
4
du
Materials:
A strong magnet ca
ti
on
imum
magnet affects the max
a
of
th
ng
re
st
e
th
if
t
Aim: To find ou
magnetic force over.
its
t
er
ex
n
ca
it
at
th
ce
distan
A weak magnet Paper clips made of steel
20
23
A
ls
to
n
E
Instructions:
1 Attach a paper clip to a strong magnet. Place another paper clip right
below the first paper clip. Continue to place the paper clips one after
another to form a chain.
Magnet
Paper clip
Stop when the additional paper clip can no longer be attracted to
the chain. Record the number of paper clips in the chain.
3
Repeat Steps 1 and 2 to get three records
for the strong magnet. Record your
results in the table on the next page.
C
op
yr
ig
h
t
2
108
Why do we need to
get three records
for each magnet?
With three records,
we can find the average of the results.
To find the average, we add up the numbers
from the three records and divide the sum
by three. The average of the results
is more reliable.
Chapter 7
4
Repeat Steps 1 to 3 for the weak magnet. Record your results below.
Number of paper clips in the chain
Magnet
1 record
2nd record
st
3rd record
Average
Lt
d
Strong
Weak
ca
ti
on
P
te
Questions:
The length of the chain tells us the maximum distance the magnet can exert its
magnetic force on the paper clips.
1 Which magnet can attract more paper clips?
2 Which magnet can exert a magnetic force over a longer distance? Why do
you say so?
ls
to
n
E
du
Conclusion:
A stronger magnet can exert magnetic forces over a ( shorter / longer )
distance than a weak magnet.
Woah! What is
happening?
ig
h
t
20
23
If I use a stronger
magnet, it can
attract the magnet
on Momo's back!
A
Strong magnets have strong magnetic fields. With a stronger magnetic field,
they can exert magnetic forces over a longer distance than weak magnets.
Solve this!
Magnet
Number of pins
A
10
B
15
Which magnet is stronger? Explain your answer.
W
C
op
yr
Jack brings two magnets, A and B, near a tray of steel pins. He records the
number of steel pins attracted to the north pole of each magnet.
k
kboo
or
Worksheet 3
Magnets
109
Crack the case
Magnets
te
Lt
d
Can exert a ___________ on another magnet
or magnetic material over a ___________
P
Beyond a ___________ distance, the
magnet will not exert any force
on
Have magnetic properties
such as
du
ca
ti
Have a ________ pole
and a ________ pole
E
Have magnetic ___________
around them where the
force of the magnet can be
experienced
Same poles
___________
Draw the magnetic field
around this magnet!
C
op
yr
ig
h
t
20
23
A
ls
to
n
Opposite poles
___________
110
The closer the magnet is to a magnetic material or another magnet,
the ___________ the magnetic force experienced. The further the
magnet is, the ___________ the magnetic force experienced.
Chapter 7
Have different magnetic ___________
Attract magnetic materials
te
such as
Lt
d
We can test if an object is a magnet by bringing it near another magnet.
If the object ___________ the magnet, the object is a magnet.
ti
Can cause a magnetic material to
become a ___________ magnet
ca
by
E
du
___________ the magnetic material
many times continuously in the
___________ direction using a
___________
ig
h
t
20
23
A
ls
to
n
Bringing a ___________ near
the magnetic material
on
P
which
t into the drain
Tie a string to a magnet. Lower the magne
to attract the name tag.
name tag out.
Lower the bag into the drain to scoop the
W
C
op
yr
of the drain
What should Tim do to get his name tag out
quickly? Tick (🗸).
the drain to
Tie a string to a pencil. Lower the pencil into
hook the name tag out.
k
kboo
or
Consolidation worksheet
Magnets
111
CHAPTER 8
Digestive System
Fried chicken
and baguettes may
not keep you strong
and healthy, Tim!
Lt
d
Tim just had a few of his tee
th extracted. His friends
would like to prepare a healt
hy lunch for him.
How should we
prepare the food
for him?
P
te
How much food
does he need
to eat?
ls
to
n
E
du
ca
ti
on
I am so hungry.
I want to eat fried
chicken drumsticks
and baguettes.
ig
h
t
20
23
A
Will you be able
to eat your food
properly?
yr
What Will I Learn
Describe the human digestive system and the functions of the organs involved.
op
State that many vertebrates have a digestive system similar to that of ours.
C
Describe how an adequate and balanced diet is important to human health.
e
What is th
o
f ur
function o
r
teeth in ou
system?
digestive
112
Chapter 8
How will the
digestion of food
be affected if
our teeth are
extracted?
What types of food
should Tim eat to
have a balanced diet?
What portions of food
should he eat?
How do the organs in our digestive system break down food?
te
Lt
d
Food needs to be broken down so that our body can absorb the
nutrients in food. The process of breaking down food is known as
digestion. In our body, a group of organs work together to digest our
food. These organs form the human digestive system.
on
Let ’s investigate!
ig
h
t
1
20
23
A
ls
to
n
E
du
ca
ti
Which organs help us to break
down our food?
P
Retrace our steps
C
op
yr
Aim: To model how the organs in the human digestive system digest food.
Materials:
Large bowl
Banana
Sealable plastic bag
Plastic bag
Newspapers
Water
Lemon juice
Plastic tray
Trash bin
Stockings
Crackers
Fork
Paper towels
Digestive System
113
ti
on
P
te
Lt
d
Mouth
Instructions:
1 Lay a table with newspapers. Place a plastic tray
on the table.
2 Place a bowl on the plastic tray. Add and mix
crackers, a banana and water in the bowl. Use a
fork to mash and break down the food in the bowl.
Questions:
1 The bowl models the mouth in our digestive system.
a What does the fork model after? Circle. ( Teeth / Tongue / Saliva )
b What does the water model after? Circle. ( Teeth / Tongue / Saliva )
A
ls
to
n
E
du
ca
Oesophagus
Instructions:
3 Transfer the contents in Step 2 into a stocking.
4 Squeeze the contents in the stocking to move them
from one end of the stocking to the other end.
Question:
2 The stocking models the oesophagus in our digestive system.
Recall what you did to move the contents from one end of the stocking to
the other end. Predict the function of the oesophagus.
20
23
_______________________________________________________
C
op
yr
ig
h
t
Stomach
You are modelling
Instructions:
what is going on in my
5 Squeeze the contents from the stocking into
stomach right now!
a sealable plastic bag.
6 Add lemon juice to the mixture in the bag.
7 Squeeze the air out and seal the bag.
8 Squeeze the bag to mash the contents in it
for a few minutes.
Question:
3 The sealable plastic bag models the stomach in our digestive system.
What does the lemon juice model after?
_______________________________________________________
114
Chapter 8
ti
on
P
te
Lt
d
Mouth
Stomach
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
Oesophagus
Digestive System
115
te
P
Collect the liquid that oozes
out of the stocking in the
plastic tray.
on
11
ti
Squeeze the contents through
the stocking.
ca
10
Lt
d
Small intestine
Instructions:
9 Cut a small hole at the corner of
the sealable bag. Transfer the
contents into another stocking.
E
du
Question:
4 The second stocking models the small intestine in our digestive system.
What does the liquid oozing out of the stocking model after?
ls
to
n
________________________________________________________________
Wrap the paper towels around the
contents. Squeeze the contents
gently to remove as much water
from the contents as possible.
yr
ig
h
t
13
20
23
A
Large intestine
Instructions:
12 Transfer the contents from the
stocking onto some paper towels.
C
op
Question:
5 The paper towels model the large intestine in our digestive system.
Based on your observations, what was removed from the digested food
in the large intestine?
________________________________________________________________
116
Chapter 8
Lt
d
te
P
ti
on
Small
intestine
20
23
A
ls
to
n
E
du
ca
Large
intestine
Anus
That looks
like poop!
C
op
yr
ig
h
t
Rectum and Anus
Instructions:
14 Transfer the contents from the paper
towels to a plastic bag.
15 Cut a hole at the corner of the plastic bag
and squeeze the contents out into a trash
bin.
Rectum
Question:
6 The plastic bag models the rectum in our digestive system.
What do the contents that were squeezed out of the hole model after?
_____________________________________________________________
Digestive System
117
1
outh
M
Food enters the human body through the mouth. Food starts to break down in
the mouth.
Teeth
When we chew
our food, our jaws
move. Our teeth
break down the
food into smaller
pieces.
ls
to
n
A
Oesophagus
The food is then
swallowed and
pushed into the
oesophagus. The
oesophagus is a
muscular tube.
The muscles in
the oesophagus
contract and relax
to push the food
down into the
stomach.
3
tomach
S
The stomach is a stretchy
and muscular bag. Food
can stay here for more
than two hours. It produces
digestive juices which help
to break down food. The
digestive juices also help
to kill germs present in
food. The stomach muscles
contract and relax to
churn food, mixing it with
the digestive juices and
breaking food into much
smaller pieces.
C
op
yr
ig
h
t
20
23
2
E
du
ca
ti
on
P
te
Tongue
The tongue helps
to push food
around, mixing
food with the saliva.
Saliva contains
substances that can
break down food.
Lt
d
Functions of organs in our digestive system
Clues
118
Chapter 8
Saliva – The liquid produced in the mouth to keep the mouth wet and to digest food
Small intestine
After a few hours in the stomach, food is then pushed into the small intestine. The
small intestine produces and releases digestive juices to break down food further.
The muscles in the small intestine contract and relax to mix the food with the
digestive juices. The muscles also help to push the food into the large intestine.
In the small intestine, most of the nutrients from food are absorbed into the blood.
ti
Large intestine
Undigested food enters the large
intestine. The large intestine
absorbs the remaining water and
mineral salts left in the undigested
food. The muscles contract and
relax to move undigested food
along the large intestine into the
rectum. The rectum is at the end
of the large intestine. In the large
intestine, the undigested food
forms waste called faeces. Faeces
are stored in the rectum before it
passes out of the body.
6
Anus
The anus is an opening at the
bottom end of the rectum. The
rectum contracts and relaxes
its muscles, pushing the faeces
towards the anus. Undigested food
leaves the body as faeces through
the anus.
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
5
on
P
te
Lt
d
4
Digestive System
119
Watch out!
A few hours after our last meal, we can feel
hungry as our stomach empties.
Lt
d
Some people may think that nutrients
from food are absorbed in the stomach.
This is because we can feel our stomachs
becoming full right after a satisfying meal.
on
P
I am hungry!
What shall we
have for dinner?
te
I am so full!
ca
ti
It feels like the stomach is empty because the food has moved into the small intestine.
The nutrients in food are absorbed in the small intestine, not the stomach!
Think-Pair-Share
E
du
Make a model of the human digestive system using recycled materials.
Draw and label your model on a poster. Present the poster and explain how your model
demonstrates the functions of each organ.
ls
to
n
How do animals digest their food?
ig
h
t
20
23
A
Humans are classified as vertebrates, which are animals with backbones.
Many vertebrates such as koalas and horses have digestive systems that are
very similar to ours. Other vertebrates such as cows have digestive systems
that are slightly different from ours.
Large intestine
Small intestine
Stomach
Oesophagus
Anus
Stomach
yr
Oesophagus
C
op
Stomach
Small
intestine
Large
intestine
Stomach
Anus
Organs in the koala's digestive system
120
Stomach
Chapter 8
Cows and many other grass-grazing vertebrates
have a stomach with four compartments. This helps
them to digest grass slowly as grass takes a long
time to break down. Unlike cows, our digestive system
cannot digest grass and other plants.
Solve this!
2
Name the organ that absorbs most of the nutrients in our food.
3
Name the organ that passes undigested food out of our body.
Worksheet 1
te
k
kboo
or
Lt
d
What is the function of the oesophagus in the human digestive system?
W
1
P
What do we need to eat and how much do we need to eat to be healthy?
ti
ca
du
Keep a diary of what you eat in a week. Note the
portions of the food eaten. One portion of food is the
amount you can fit onto the palm of your hand. If the food
has nutritional labels, paste them in your diary as well.
on
I am going to
have one portion
of spaghetti!
Think-Pair-Share
ls
to
n
E
Diet refers to the food we eat. In order for us to be healthy, we need to have an
adequate and balanced diet.
20
23
A
Adequate diet
We need to have an adequate diet to survive. An adequate diet refers to the
right amounts of food required by our body to stay alive and carry out life
processes. We need to eat enough to obtain the energy needed to carry out
our daily activities. An adequate diet may or may not be balanced.
C
op
yr
ig
h
t
I do not eat vegetables
and meat.
Cyrus has an
adequate diet but his diet is
not balanced. He needs to eat
vegetables and meat too, so
that he has a balanced diet!
Digestive System
121
Lt
d
Balanced diet
To stay alive and be healthy, we also need to have a balanced diet.
A balanced diet consists of different types of food in the right amounts. We
can use a food plate as a guide for the types and amounts of food we should
eat in a balanced meal.
Fruits and
vegetables
ca
ti
on
P
te
Carbohydrates
du
Proteins
Dairy
Functions
Give us energy
Proteins
Help our body grow
Help repair our body
Oils and fats
Give us energy
Dairy
Help our bones grow
Fruits and
vegetables
Help our body to fight
diseases
Help us to pass
undigested food out of
our body
20
23
ig
h
t
yr
op
A
Carbohydrates
C
122
ls
to
n
Food group
E
Oils and fats
This food plate shows
the recommended
daily portion for each
food group in the
Eatwell Guide from the
United Kingdom.
Other countries may
recommend different guides
for a balanced diet. Watch
this video to find out about
the food plate in Singapore's
health guide.
Water is important for
many processes that
keep us alive.
A balanced diet includes water. We should
drink at least six to eight glasses of water
every day.
Chapter 8
Find out more
about the Eatwell
Guide on this
website.
Lt
d
A teaspoon of salt
is about 6 g.
te
Salt and sugar in our food
To stay healthy, we need to monitor the amount of salt and
sugar in our diet. The Eatwell Guide recommends that children
between 7 to 10 years old should not take more than 5 g of
salt a day. Adults and children who are 11 years old and above
should not take more than 6 g of salt a day.
on
P
Sugar occurs naturally in food such as fruits, milk and vegetables. Processed
food such as canned fruits may contain added sugar known as free sugar.
We should not have
more than 30 g of free
sugar a day.
ls
to
n
E
du
ca
ti
We should not have
more than 24 g of
free sugar a day.
Children from 7 to 10 years old 24 g
Adults
30 g
A
The recommended amount of free sugar in our diet
Check the nutritional
labels you have
collected in your food
diary. Are you eating
food that contains too
much sugar or salt?
Sodium is salt.
C
op
yr
ig
h
t
20
23
We can monitor the amount of sugar and salt in our food by checking the
nutritional labels on food packaging.
Clues
Processed food – Food that has been cooked, canned, frozen, packaged or prepared in a
way to improve its taste or to make the food last longer without spoiling
Digestive System
123
Solve this!
The children are preparing these food for Tim on his
birthday:
te
P
on
ti
What happens to our health if our diet is poor?
Lt
d
Broccoli
Grilled chicken
Yoghurt
Rice
Chocolate
Orange
On the plate on the right, mark and label the portions
of food Tim should eat in order to have a balanced diet.
ca
Think-Pair-Share
E
du
Using the Internet or books, research and find answers to the following questions.
What happens if our diet is inadequate?
What happens if our diet lacks any of the food groups recommended in the food plate?
If we have a poor diet, what health problems will we have?
ls
to
n
Undereating
If we eat less than what is required by our body, we will not have enough
energy and nutrients to thrive and grow properly.
What happens if we eat too little of this food group?
A
Food group
Not enough energy
Proteins
Cannot grow well
Oils and fats
Dairy
20
23
Carbohydrates
Bones may be formed poorly
ig
h
t
Fruit and vegetables
Fall sick easily
Hard for us to pass undigested food out of our body
yr
Overeating
We should not overeat.
If we eat more than what is
required by our body, we may
gain weight unhealthily and
experience health problems.
op
C
Not enough energy
124
Chapter 8
What happens if we eat too much of this food group?
Carbohydrates
May develop diabetes
Proteins
May damage kidneys
Oils and fats
May develop heart problems and diseases
Dairy
May cause bloating and diarrhoea
Fruit and vegetables
May develop diabetes if we eat fruits that contain a lot of sugar
May cause bloating if we eat too much vegetables
te
Too much salt or sugar
Lt
d
Food group
P
Think-Pair-Share
on
Using the Internet or books, research and find out what will happen to us if we eat food
containing too much salt or sugar.
ls
to
n
E
du
ca
ti
Too much salt in our diet puts us at risk of developing heart diseases.
Too much sugar in our diet increases the risk of developing diabetes. Diabetes
is a disease that affects how our body processes sugar. This causes sugar
to remain in the blood. Over time, people with diabetes may develop other
diseases, such as heart diseases and nerve disorders.
Science in context
ig
h
t
20
23
A
I am a dietitian. I help my patients to plan their meals and teach them how to prepare their
meals healthily. Patients suffering from certain diseases may be taking medicines that can be
affected by the type of food they eat. I help by planning special diets for them.
yr
Watch this video to
find out more about
a dietitian's job.
Watch out!
C
op
What about animals? Do they have the same diet as humans? Different animals have
different requirements for their diet. Some animals may not survive well if they follow our
food plate guide.
Do I need to have
the same balanced
diet as you?
What about me?
Do I need to eat
like you?
Digestive System
125
Solve this!
What happens if we frequently eat foods that are high in salt?
W
3
What may happen to our health if we have too many portions of carbohydrates
in our diet?
Lt
d
2
What will happen if we eat more than what our body requires?
k
kboo
or
P
Science in context
Worksheet 2
te
1
on
In the olden days, food was limited and machines were not invented yet.
Many people did hard labour work.
A
ls
to
n
E
du
ca
ti
We eat a lot of
carbohydrates. It
gives us energy to
do work.
C
op
yr
ig
h
t
20
23
Today, we use machines to make our work easier. Most of our work does not
require much labour now. As such, we are not as active as people in the olden
days.
Many people work in offices these days. They
spend a large amount of time seated at their desks.
We use machines to help
us with labour work.
As our lifestyles change, the needs of our bodies change too. The diet of
humans in the past may not be adequate and healthy to us now.
126
Chapter 8
make up
Food
Digestive
System
Diet
te
P
Many vertebrates
are similar to that
of ours
ti
on
In order to be healthy
ca
Human
Tim had some of his teeth extracted.
Which plate of food is suitable and
healthy for him? Tick (🗸).
du
Mouth
ls
to
n
E
Breaks down food
using _______ and
saliva
_______________
20
23
A
Pushes food down
into _______
Produces
_____________ to
break down food
ig
h
t
_______________
W
C
op
yr
Produces
_____________
and absorbs
_____________
Rectum
Pushes faeces
towards anus
_______________
_______________
Absorbs water and
forms _____________
Passes faeces out
k
kboo
or
Balanced
Eat _________
types of food in
the right amounts
Eat the _________
amount of food
in
Stomach
should be
Adequate
Lt
d
breaks
down
Crack the case
Consolidation worksheet
Blended
broccoli and
apple juice
Mashed
potatoes
Carrot
soup
Soup with
soft pieces of
chicken and
eggs
Milk
Cheese
Oil and
dip
butter
Steamed
French fries
broccoli and
carrots
Boiled
Apple
potatoes
slices
Chicken
fillet
Milk
Oil and
butter
Cheese slices
Mashed
potatoes
Soup with
soft pieces
of chicken
and eggs
Blended
broccoli
juice
Milk
Oil and
butter
Cheese dip
Digestive System
127
CHAPTER 9
te
Tim and Cyrus are helping the
zoologist to welcome a new
animal. They need
to find an enclosure that is ve
ry similar to the natural habit
at of the animal to
house it. As the animal will be
sharing the same enclosure
with other animals,
Tim and Cyrus need to find ou
t whether this animal is a pre
dator or prey, so
that this animal does not ea
t other animals or get eaten
by other animals.
This animal has
blunt teeth and its eyes are
at the sides of its head.
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
on
P
It has thick, white
fur. What kind of
environment does this
animal live in?
C
op
yr
What Will I Learn
128
Describe how animals are adapted to environments that are
hot, cold, wet or dry.
Describe some adaptations of predators and prey.
of
What type
ent
environm
with
do animals
e fur
thick, whit
live in?
Chapter 9
Lt
d
Adaptations of Animals
What type of
food does the
animal feed on if
it has blunt teeth?
How are the
eyes of a prey
and a predator
positioned?
What are adaptations?
Retrace our steps
on
P
te
Lt
d
Adaptations are characteristics of animals that
What is the
difference
allow the animals to thrive in an environment.
between thriving
To thrive in an environment, animals need to
and surviving?
have adaptations for the following:
To obtain and eat food
To escape from danger and avoid being eaten by other animals
To cope with extreme conditions
To reproduce to ensure their kinds do not become extinct
Think-Pair-Share
ca
ti
What is the most important adaptation for animals? Discuss.
E
du
What adaptations do animals have to obtain
the food they eat?
ls
to
n
Think-Pair-Share
What is a
predator and
a prey?
Oh no, the snake is
going to eat the bird!
ig
h
t
20
23
A
What is in the
bird's mouth?
Retrace our steps
It is eating a grasshopper.
What helps the bird to
catch the grasshopper?
C
op
yr
Which are prey? Which are predators? Can you identify the adaptations each
predator has to help it catch its prey?
Watch out!
Can a predator be a
prey too? Can a prey be
a predator too?
Some animals can be both a predator and prey.
These animals have adaptations to help them catch other
animals for food. They also have adaptations to help
them escape from other animals that feed on them.
Can you think of other examples of animals that are both
predator and prey?
Adaptations of Animals
129
Let’s investigate!
1
Classification key Two hula hoops
te
Materials:
Set of animal picture cards Lt
d
.
ey, or predator and prey
pr
,
or
at
ed
pr
as
s
al
im
an
Aim: To classify
ti
on
P
Instructions:
1 Place hula hoops on the floor according to the diagram below. Label the
groups within the hula hoops accordingly.
du
ca
Predator
and prey
Predator
20
23
A
ls
to
n
E
Prey
Read the characteristics stated in the animal cards. Predict and classify the
animals on the cards into the different groups.
3 Check your classification using the classification key given to you.
ig
h
t
2
C
op
yr
Questions:
1 Which animals are both predator and prey?
2 Compare the characteristics of the animals within each group.
a How are the characteristics of the animals in the predator group similar
to one another?
b How are the characteristics of the animals in the prey group similar to
one another?
130
Chapter 9
Animals have different adaptations to help them obtain the food they eat.
Adaptations for movement to catch prey
Lt
d
Think-Pair-Share
on
P
te
What adaptations does a cheetah have to move fast?
du
ca
ti
What does a
cheetah eat?
ls
to
n
E
Predators need to hunt other animals for food. They need to have adaptations
to help them respond and move quickly to catch their prey.
The cheetah’s tail
balances its movement.
It allows the cheetah to
turn fast without falling.
The cheetah has a narrow
body and a very flexible
backbone. A narrow body
reduces air resistance. A
flexible backbone allows it to
bend its body and take big
steps when it runs.
ig
h
t
20
23
Its claws act like
running spikes
to help it grip
the ground as
it runs.
A
The cheetah has
long, strong legs
so that it can take
big steps as it runs.
C
op
yr
The cheetah is the fastest land animal on Earth. It is an excellent hunter.
The lion has strong legs to run fast and catch its prey.
Adaptations of Animals
131
on
P
te
Lt
d
Birds that hunt have strong wings to help them fly fast. They have different wing
shapes that suit their hunting style.
du
ca
Birds with long, narrow wings
can fly very fast. They can
change direction quickly too.
20
23
A
Adaptations to hold
onto prey
Predators have strong paws
and sharp claws to help
them grip onto their prey.
ls
to
n
E
Birds with broad and flat wings can stay in
the air for long hours. They have feathers
with pointed, finger-like tips at the end
of their wings. These feathers allow the
birds to change direction quickly.
ti
Feather with a finger-like tip
Predators with sharp
claws to grip onto their prey
C
op
yr
ig
h
t
Adaptations to sense prey
Predators usually have eyes at the front of their heads. This allows them to
spot their prey easily and judge their distance to the prey accurately so that
they can catch their prey.
Predators with eyes at the front of their head
132
Chapter 9
ca
ti
on
P
te
Lt
d
Besides having eyes at the front of their head, predators that hunt at night
have large eyes. Both characteristics help the predator to spot and hunt its
prey in the dark.
E
ls
to
n
20
23
Lions can hear prey that
are as far as 1.6 km away!
The lions must
have heard the
wildebeests!
Time to hunt!
A
Predators usually have
a good sense of hearing
and smell to help them
detect their prey that
are very far away.
du
Predators that hunt at night
ig
h
t
Adaptations to prevent predators from being spotted by their prey
Think-Pair-Share
yr
Can you spot the snow leopard in this
picture?
C
op
What helps the snow leopard to blend
into its surroundings?
How does that help the snow leopard
in hunting?
Adaptations of Animals
133
Lt
d
Some predators have an outer
covering that can help them to
blend into the surroundings of
their habitat. This is known as
camouflage.
on
P
te
The scorpionfish camouflages and waits
for its prey. It sucks the prey into its mouth
when the prey swims past it.
ti
What adaptations do animals have to help them feed on food?
ca
Think-Pair-Share
Seeds
Insects, worms and other animals
E
Fruits
Nectar
du
Birds have different types of beaks to help them feed on different types of food. Using the
Internet or books, research to find out about the beaks of birds that feed on the following:
ls
to
n
Draw the beaks of the birds and discuss how the different beaks help the birds to obtain the
food they eat.
Birds have different beaks that are adapted to feed on different types of food.
Birds that feed mainly on seeds have
short and sharp beaks to help them
crack open seeds.
C
op
yr
ig
h
t
20
23
A
Birds that feed mainly on fruits have
large beaks to help them crush fruits
or pluck fruits off the plant.
Birds that feed mainly on other animals usually
have sharp, hooked beaks. The beaks help
these birds to tear and rip the flesh of their prey.
134
Chapter 9
on
P
te
Lt
d
Some birds are omnivores. They feed on
plants and other animals. The hummingbird
feeds on small insects and nectar in flowers.
They have long, thin, needle-like beaks to
help them reach into the flowers for nectar.
The needle-like beaks are also sharp to help
them reach and pierce small insects hiding in
narrow spaces.
E
du
ca
ti
Some birds that feed mainly on fish have
long, straight and sharp beaks. The beaks
help them to spear fish in the water.
ig
h
t
20
23
A
ls
to
n
Other birds that feed on fish have large, curved beaks. They help the birds to
scoop fish from the water.
Retrace our steps
yr
Think-Pair-Share
C
op
What types of teeth do carnivores, herbivores and omnivores have?
Draw and describe.
What are the
three different
types of
consumers?
Watch the video to
see how the teeth
of different types
of consumers are
adapted for feeding!
Adaptations of Animals
135
Carnivores have long and sharp
front teeth which help them catch
and tear the meat of their prey.
ti
on
P
te
Lt
d
Herbivores have broad and blunt
teeth to help them grind up plants.
ls
to
n
E
du
ca
Omnivores have sharp teeth to help them tear meat and blunt teeth to help
them grind up plants.
Sharp tooth
Sharp tooth
A
Blunt tooth
Blunt tooth
20
23
What adaptations do animals have to help them escape from danger?
ig
h
t
While it is important to be able to obtain and feed on food, animals also have
adaptations to help them escape from danger and avoid being eaten by
predators.
C
op
yr
Adaptations to move and escape from predators
Animals need to be able to run fast so that they can escape from their predators.
136
Think-Pair-Share
What helps herbivores escape
from their predators?
Chapter 9
Watch this
video to
find out!
Lt
d
Hooves
te
Large herbivores have thin, long
legs with strong muscles that allow
them to run fast and escape from
their predators. They also have
hooves that allow them to run
fast over long periods of time.
A school of fish looks like
a big fish from above! This
will scare predators such as
birds away.
20
23
A
ls
to
n
E
du
ca
ti
on
P
Adaptations to defend themselves from predators
Many animals have adaptations that allow them to defend themselves.
Herbivores use their strong legs to kick their predators so that they would have
the chance to escape. Some have horns on their head that they can use to
attack their predators. They also travel in herds to help one another if a predator
tries to attack them. Some herbivores can even produce a special sound to warn
others in the group when they spot their predator.
Wildebeests travelling in a large herd
Small fishes travelling in a large group
Think-Pair-Share
yr
ig
h
t
Using the Internet or books, research to find out how octopuses, porcupines and pufferfish
defend themselves from their predators.
C
op
Some animals defend themselves from their
predators by frightening or threatening them.
The porcupine is covered with spikes called quills.
It will raise its quills when it senses danger. The quills
make it look more dangerous to its predators. The
porcupine may also stab its predators with its quills
to frighten them away.
Adaptations of Animals
137
Lt
d
te
P
on
The pufferfish has spikes. It can puff up when
it senses danger. The spikes make it difficult for
the predator to eat the pufferfish.
ti
The octopus will release black ink to blind
its predators so that it has time to escape.
du
ca
Some animals have bright and colourful
outer covering to warn their predators.
These animals are usually poisonous.
ls
to
n
E
Poison dart frog
ig
h
t
20
23
A
Adaptations to hide from predators
Small animals that cannot run fast will need to find other ways to protect
themselves from predators.
yr
Rabbits and some frogs dig burrows to hide from their predators.
C
op
Some animals hide in their shells when they
sense danger. The shells are usually hard. So, it
is difficult for predators to eat these animals.
A tortoise hiding in its shell
138
Chapter 9
Why is there a
hole here?
Adaptations to avoid being spotted by predators
ti
E
du
Adaptation of sight to spot predators
Some animals have their eyes at the sides of
their head. This feature allows the animals to
have a wider view of their surroundings so that
they can detect predators nearby.
on
P
te
Can you think of any
other animals that have
adaptations to help them
camouflage and hide from
their predators?
ca
The dead leaf
butterfly has wings
that look like dead
leaves which are
commonly found
in its habitat.
Lt
d
Some animals can camouflage to blend into their surroundings. This
makes it difficult for their predators to spot them.
ls
to
n
Solve this!
Two animals are shown on the right.
X
Y
W
20
23
A
Which animal is a predator?
Describe an adaptation that helps this
animal to catch its prey.
Which animal is a prey? Describe an adaptation that helps this animal to
escape from its predator.
k
kboo
or
Worksheet 1
ig
h
t
What adaptations do animals have to help them reproduce?
yr
Animals have adaptations to attract a mate to reproduce. Some use colours
and sounds to do so. Others use special movements.
C
op
Watch how
the frigate
bird attracts
its mate in
this video!
A male frigate bird makes
special movements to attract
female frigate birds.
Adaptations of Animals
139
What adaptations do animals living in a hot and dry environment have?
You will be surprised!
Some animals can thrive in
environments with extreme
conditions. They have
adaptations to cope with
their surroundings.
Lt
d
Watch out!
on
P
te
It is so hot here. There
is no water. Can any
living thing survive in
the desert? I do not see
any animals around.
du
ca
ti
We can find animals living in an environment that is very hot and dry such as
the desert. In a desert, animals have adaptations to help them obtain water,
reduce water loss and cope with the extreme heat.
Think-Pair-Share
ls
to
n
E
Using the Internet or books, research to find out about the animals that live in the desert.
What adaptations do these animals have? Present your findings in a poster.
20
23
A
Adaptations to obtain water
Most animals in the desert obtain water from the food they eat. Animals such
as camels obtain water by eating plants such as cacti. Camels have a hard
covering inside their mouth to protect them from the spines of the cactus
that they eat.
Cactus
Camel
C
op
yr
ig
h
t
Other animals such as the desert
beetle have bumps on its body to
help collect water from the air. Water
droplets that have condensed on its
body can flow into its mouth.
140
Chapter 9
OUCH!
Desert beetle
P
te
Lt
d
Adaptations to reduce water loss
Since most water is lost through urine, many desert animals have adaptations
to produce less urine so that they lose less water from their body.
These animals also have adaptations to reabsorb a lot of water from the food
in the intestines during digestion. As a result, the faeces of these animals are
usually very dry. Camels have very long and large intestines that allow them to
reabsorb the water from the food they eat.
du
ca
ti
on
Some animals such as the cactus wren have special
adaptations inside their nose to help them condense water
vapour in the air that they breathe out into water droplets.
These water droplets will be taken into the body together with
the air that they breathe in.
Cactus wren
E
Adaptations to cope with extreme heat
Animals such as the camel have adaptations
to prevent overheating. Camels store most of
their fats in their humps. As fats trap heat, this
adaptation prevents the rest of the camel's body
from absorbing and retaining too much heat.
Camel
C
op
yr
ig
h
t
20
23
A
ls
to
n
Hump
Fennec fox
Some desert animals have adaptations to help
them avoid heat.
Cape ground squirrels dig and live in burrows
underground. This behaviour protects them from
the heat and their predators.
Animals such as the fennec fox
have very big ears that help to
remove excess heat from its
body on a hot day.
Cape ground
squirrel
Adaptations of Animals
141
What adaptations do animals living in a cold environment have?
Watch out!
It is so cold in
the Arctic! Can
living things
survive here?
P
te
Lt
d
It is possible if the
animals have the
adaptations to cope
with the cold! Brrr...
on
Think-Pair-Share
ca
ti
Using the Internet or books, research to find out about the animals that live in the Arctic. What
adaptations do these animals have? Present your findings in a poster.
E
du
In places such as the Arctic, animals have adaptations to help them to cope
with the extreme cold.
ls
to
n
Adaptations to cope with the extreme cold
Animals living in an extremely cold environment have adaptations to retain
heat and reduce heat loss to their surroundings.
20
23
A
Many animals such as polar bears have thick fur and a thick layer of fat
under their skin to keep them warm. Animals such as the bowhead whale and
ringed seal have thick layers of fat known as blubber to keep them warm in
cold waters.
ig
h
t
Birds like the snowy owl have double layers of feathers to keep them warm.
Polar bears and Arctic foxes have small ears to reduce heat loss to their
surroundings.
C
op
yr
Ringed seal
Bowhead whale
142
Chapter 9
on
P
te
Lt
d
Some animals have adaptations to hide from the cold. For example,
the mother polar bear digs dens to house herself and her cubs to
protect them from the cold.
ti
Snowy owl
The polar bear has thick,
rough paws to help it move
fast and prevent it from
slipping on the ice or snow.
Polar bear cubs
hiding in the den
The layers of snow
provide insulation and
keep the den warm.
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
Polar bear
The Arctic fox has furry
feet to prevent it from
slipping on the ice.
Adaptations of Animals
143
ti
on
P
I cannot hold my
breath for too long
underwater. I need to
come up to the surface
to breathe!
te
Why are we not
able to breathe
underwater?
Lt
d
What adaptations do animals living in water have?
Think-Pair-Share
E
du
ca
Using the Internet or books, research to find out
about the adaptations animals have so that they
can live in water. Present your findings in a poster.
C
op
yr
ig
h
t
20
23
A
ls
to
n
Adaptations to breathe in water
Fish and most underwater animals have gills
to help them breathe and take in oxygen
underwater.
144
Chapter 9
Gills
Blowhole
on
P
te
Lt
d
Some animals that live in water do not
breathe through gills. For example,
whales and dolphins are marine
mammals that breathe through their
lungs. These animals make frequent trips
to the water surface to take in air through
their blowholes.
A
ls
to
n
ca
du
E
It is difficult for animals to move in water
due to water resistance.
Bodies of animals living in water have a
narrow front that reduces the surface
area in contact with water. We say that
these animals have a streamlined body.
A streamlined body experiences less
water resistance, allowing the animal to
move faster in water.
ti
Adaptations to move in water
What is the force
that acts against
our movement in
water?
Fin
ig
h
t
20
23
Most animals who live in water have fins,
flippers and tails to help them balance
and move in a straight line in water.
Tail
Flipper
Can you find the
fins, flippers and
tails of the other
animals here?
C
op
yr
Retrace our steps
Adaptations of Animals
145
Let’s investigate!
2
( Hot / Cold )
( Dry / Wet )
E
The pictures below show animals that can be found in the different
environments shown in Step 1.
ls
to
n
2
( Hot / Cold )
( Dry / Wet )
du
( Hot / Cold )
( Dry / Wet )
ca
ti
on
P
te
Instructions:
1 Circle the words that can be used to describe each environment.
A
B
C
Lt
d
rent environments.
ffe
di
in
d
un
fo
be
n
ca
at
als th
Aim: To predict the anim
Reindeer
Kangaroo rat
20
23
A
Beluga whale
yr
ig
h
t
Using the Internet or books, research to find out about the different habitats
these animals live in. Then, research the adaptations these animals have to
help them thrive in their habitats.
You may use the headings of the table below to help you organise your findings.
C
op
Name of the animal
Tick (🗸) the environmental
condition(s) that the animal is
adapted to.
Hot
Cold
Dry
Wet
Others: ______
146
Chapter 9
Describe the adaptations of
the animal.
Question:
Based on your findings, predict and match the animals to the environment
they are found in.
A
P
te
Lt
d
Beluga whale
on
B
du
ca
ti
Reindeer
Kangaroo rat
Solve this!
20
23
A
ls
to
n
E
C
Has big ears and
produces very little urine
Cold
Has gills and a
streamlined body
Hot
Has small ears and a thick
layer of fat under its skin
Underwater
W
C
op
yr
ig
h
t
Match the adaptations of each animal to the correct environmental conditions
that it can be found living in.
k
kboo
or
Worksheet 2
Adaptations of Animals
147
Crack the case
Thrive as predator and/or prey
have
adaptations to
Lt
d
Animals
Reproduce
te
by
P
on
Predators have
adaptations to
obtain food
ca
such as
Feed on food
du
Avoid being _________
by predators
such as
Using _________,
sounds and special
______________ to
attract a mate
ti
Prey have adaptations to
escape from predators
by
ls
to
n
E
Having sharp or blunt ________________
Having sharp, short, needle-like
or long ______________
20
23
_________ itself
from predators
A
_________
from predators
ig
h
t
Spot predators so
that they escape
quickly
C
op
yr
_________ quickly
away from predators
_________ their
prey
Avoid being
spotted by prey
Hold onto their prey
Move quickly to catch their prey
148
Chapter 9
Gills to___________
underwater
such as
Water
Lt
d
have adaptations
to live in
te
________________ body to
_____________ quickly in water
on
Cold
environment
such as
du
___________
from the cold
by digging dens
ls
to
n
E
Reduce ___________
loss by producing
___________ urine or
reabsorbing water from
food in the intestines
Small ears to reduce
___________ loss
20
23
A
Cope with extreme
heat by ___________ in
burrows, having big ears
or only storing fats in
some parts of the body
Thick layer of
___________
under skin
ti
such as
ca
Cope with the
lack of water by
obtaining water
from food and air
___________ fur
P
Hot and dry
environment
ig
h
t
mal live in?
What kind of environment does the new ani
Is it a predator or prey? Tick (🗸).
ment.
It is a predator living in a hot and dry environ
It is a predator living in a cold environment.
It is a prey living in a cold environment.
It is a predator that lives in water.
It is a prey that lives in water.
W
C
op
yr
nt.
It is a prey living in a hot and dry environme
k
kboo
or
Consolidation worksheet
Adaptations of Animals
149
CHAPTER 10
Sound
on
P
te
Lt
d
Tim is playing his drum to pra
ctise for a school
performance. His mother co
mes in to tell him to
lower the volume as it is alrea
dy late at night.
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
ti
My performance is
happening tomorrow!
What can I do to lower
the volume?
op
What Will I Learn
How is soun
d
produced?
C
✓ Investigate how sounds are produced by vibrating sources.
✓ Describe sounds in terms of pitch and volume.
✓ Investigate how the volume and pitch of sounds can be changed.
150
Chapter 10
he
What is t
fa
volume o
sound?
What affects
the volume o
f
sound made
by
a drum?
How is sound produced?
Retrace our steps
Twinkle, twinkle
little star…
on
P
I can make music
with this!
te
Place your fingers on your throat and make a sound.
Lt
d
How does an
object move when
it produces a
sound?
Think-Pair-Share
ti
What did your
fingers feel?
ls
to
n
E
du
ca
How does the rubber
band move when
you pluck it?
The rubber band vibrates and makes a
sound when we pluck it. The rubber band is
a vibrating source.
ig
h
t
20
23
A
Sound is produced when an object
vibrates. When an object vibrates,
it moves back and forth quickly
and repeatedly. When an object
vibrates, it is a source of sound. We
refer to the vibrating object as the
vibrating source.
Think-Pair-Share
C
op
yr
Find out how the following instruments make sounds.
How does each instrument make vibrations?
Which instruments are similar to each other?
Classify the instruments into groups based on how they make vibrations.
Sound
151
Musical instruments can be classified as string, wind or percussion instruments.
on
P
te
Lt
d
When we pluck the strings of a guitar or draw a bow across the strings of a
violin, the strings vibrate to produce sounds.
Guitar
Violin
ti
Examples of string instruments
Examples of wind instruments
Clarinet
A
Trumpet
ls
to
n
E
du
ca
When air is blown into a trumpet or a clarinet, air particles inside the
instrument vibrate to produce sounds.
C
op
yr
ig
h
t
20
23
When we hit a drum using a drumstick or our hands, the drum skin vibrates
to produce sounds. When we hit a gong with a mallet, the gong vibrates to
produce sounds.
Drum
Metal gong
Examples of percussion instruments
Think-Pair-Share
Hit a tuning fork against the palms of your hands. Do you hear a
sound? Dip the tuning fork into a cup of water. What happens to the
water surface? What causes this to happen?
152
Chapter 10
Tuning fork
Water
How does sound travel to our ears?
Let’s investigate!
travels.
te
Materials:
Speaker Metal container
Plastic film Bowl Which sense organ helps
us to hear sounds?
What are some sources
of sound?
P
und
Aim: To find out how so
Lt
d
Retrace our steps
Metal spoon
Rice grains
on
1
ls
to
n
E
du
ca
ti
Instructions:
1 Stretch a plastic film over a bowl.
2 Place some rice grains on the plastic film.
3 Play some music through the speaker. Bring the speaker near the rice
grains on the plastic film.
Rice
grain
Plastic
film
A
Bowl
Speaker
ig
h
t
20
23
What happens to the rice grains? ____________________________
4 Turn off the music. Make some sounds near the rice grains by hitting a
metal container with a metal spoon.
What happens to the rice grains? ______________________________
C
op
yr
Questions:
1 What are the vibrating sources in Steps 3 and 4?
________________________________________________________________
2 Using your knowledge of the particle model, infer what could have
happened to the air particles near the vibrating source to cause the effect
observed in the rice grains?
___________ particles near the vibrating source start to vibrate and collide
with one another. The vibrating ___________ particles then collide with the
___________. This causes the ___________ to vibrate, which causes the rice
grains to ___________.
Sound
153
Most of the sounds we hear travel through air. Air in our surroundings contains
air particles.
Lt
d
When an object vibrates, it collides with the surrounding air particles. This
causes the air particles to start to vibrate too.
te
Tuning fork vibrating
du
ca
ti
on
P
Watch the animation
below to find out how a
vibrating source affects its
surrounding air particles.
ls
to
n
E
The vibrating tuning fork vibrates. Some groups of air
particles are pushed close together, while other groups of air
particles are pulled apart.
Sound does not move
between the air particles. It
is the air particles that are
moving and transferring
sound energy.
C
op
yr
ig
h
t
20
23
A
The air particles collide with even more air particles, causing them to vibrate
too. These vibrations travel in waves. We call them sound waves.
The regular movement of air particles forward
and backward creates a sound wave.
Sound waves travel away from the vibrating source. When the waves reach
our ears, we hear the sound.
154
Chapter 10
If I go to space,
no one can hear me!
I can practise my
violin there!
Lt
d
Sound needs particles to travel. The space
containing particles where sound can travel through
is called a medium. We say that sound needs a
medium to travel. The medium can be a solid, liquid
or gas.
P
on
ti
I can see you
playing the
cymbals but
I cannot hear
them.
20
23
A
ls
to
n
E
du
ca
nd
, sou
e
c
ay
a
In sp ravel aw g
t
tin
ot
cann the vibra
from ource!
s
Cyrus, how does
this sound?
te
In outer space, there are no particles. We say that
the outer space is a vacuum. Without particles,
sound cannot travel in outer space.
Can sound travel through solids and liquids?
ig
h
t
Sound travelling through solids
Think-Pair-Share
yr
Place your ear on the surface of a table. Get your classmate to
scratch lightly on the table using their fingernail.
Do you hear any sound?
C
op
Why were you able
to hear the sound?
Discuss.
Sounds can travel through solids too.
Sound
155
How do sounds travel through solids?
2
Let’s investigate!
Instructions:
1 Make a hole at the base of each paper cup.
te
ca
Thread one end of the string through the hole in
one of the cups. Thread the other end through the
other cup. Tie a knot at each end of the string on
the inside of the cup.
E
du
2
P
Scissors
on
A piece of long string ti
Materials:
Two paper cups Lt
d
string affects how well
a
of
ss
ne
ht
tig
e
th
w
Aim: To find out ho
sound travels.
Get a classmate to hold one of the cups while
you hold the other. Move away from each other
such that the string between the two of you is
pulled tightly.
Take turns to whisper into the cup and
listen through the cup. Can you hear
each other? _______
String
pulled
tightly
Now, move a few steps closer to each
other until the string is hanging loosely or
slack. Whisper into the cup again.
Can you hear each other? _______
yr
ig
h
t
4
20
23
A
ls
to
n
3
Conclusion:
Sound can travel through the string when the string between the cups is
_____________.
Sound cannot travel well when the string between the cups is ______________.
op
C
String hanging loosely
or slack
156
Chapter 10
o!
oo
on
P
H
o!
oo
ello
te
ello
H
Lt
d
I can hear Tim's
voice!
ca
ti
When the string is pulled tightly, we can hear each other.
A
ls
to
n
E
du
When we speak into the cup, the air particles vibrate. This causes the cup to
vibrate. The vibrations are then transferred from the cup, through the pulled
string to the other cup. The other cup vibrates and causes the surrounding air
particles to vibrate too. These vibrations reach the ear of the listener, allowing
the listener to hear the sound.
20
23
o!
oo
ello
C
op
yr
ig
h
t
H
I cannot hear
Tim as much
anymore.
When the string is hanging loosely or slack, we cannot hear each other well.
When the string is slack, vibrations cannot transfer well through the string.
Less vibrations reach the ear of the listener. The listener cannot hear the
sound as well.
Sound
157
Sound travelling through liquids
Lt
d
te
on
du
ca
ti
Air particles above water can collide with liquid particles in
water. When Ada sings on land, the vibrating air particles
collide with the liquid particles, causing liquid particles to
vibrate too. This is how sound waves from the air reach
Vera's ears in water. So, even in water, Vera can hear Ada's
singing from the land!
Under the sea...
Can you hear me?
P
Sounds can travel through liquids too. When Vera swings the
bell, the vibrating bell collides with the liquid particles in the
water. The liquid particles collide with other liquid particles,
causing them to vibrate too. Just like in the air, these
vibrations travel as sound waves in liquids too.
When sound waves reach our ears, we can hear
sounds in water!
My arms are
aching!
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
This is hard! I am
so tired!
158
Chapter 10
Meooooowwwww...
Meooowwww...
I can hear Ada's
singing! I can hear a cat
meowing too!
Solve this!
on
How does our body help us make different sounds?
P
te
Lt
d
Jenny hears a sound when she hits a metal cup with a metal spoon.
Describe how Jenny hears the sound.
ti
Think-Pair-Share
ca
Place your fingers on your throat.
Make a low sound and a high sound.
E
du
What did your fingers feel?
Was there any difference between the
low and the high sound?
20
23
A
ls
to
n
We use the vocal cords in our throat to make sounds.
When we speak or sing, air is pushed from our lungs to
our vocal cords. This makes our vocal cords vibrate,
which causes the surrounding air particles to vibrate
too. The vibrations of the surrounding air particles
produce the sounds we make when we speak or sing.
Vocal cords
W
C
op
yr
ig
h
t
Our vocal cords can move differently to produce different types of
vibrations. This is how we can make different sounds!
k
kboo
or
Worksheet 1
Sound
159
How do we describe sounds?
Retrace our steps
Pitch
The pitch of a sound refers to how high or low a sound
is. Sounds can be high or low, depending on how fast
the vibrations are. The faster the vibrations, the higher
the pitch of the sound. The slower the vibrations, the
lower the pitch of the sound.
Lt
d
What are some
words we can
use to describe
sounds?
te
Think-Pair-Share
ti
on
P
Listen to a high note and a low note on a guitar.
Can you hear the difference between the two sounds?
Can you tell which is the higher and lower note?
Look at the strings that produce the different notes when
plucked. How are they different from each other?
ls
to
n
E
du
ca
The strings on a string instrument have different thickness.
The difference in thickness allows the strings to produce
sounds of different pitches. When a thicker string is plucked,
it produces sounds of a lower pitch. When a thinner string is
plucked, it produces sounds of a higher pitch.
Think-Pair-Share
A
A thick string on a guitar produces a low-pitched note.
What can we do to the same string on the guitar to make the pitch higher?
yr
ig
h
t
20
23
The length of the string plucked also affects the pitch of the
sound produced.
When plucking a string that is short,
a high-pitched note is produced.
C
op
When plucking a string that is long,
a low-pitched note is produced.
Long string
Short string
On a guitar, we can use our fingers to press against the string to shorten
the length of the string that can vibrate when plucked.
160
Chapter 10
I can make a louder
sound by hitting the
drums harder using the
drumsticks.
te
Lt
d
Volume
Sounds can be loud or quiet. We call this the volume of a sound.
We can make loud sounds by shouting and quiet sounds by whispering.
We can also make loud and quiet sounds using musical instruments by
changing the way we play them.
on
P
I can make a
louder sound by blowing
harder into the trumpet.
20
23
A
ls
to
n
E
du
ca
ti
I can make a louder sound
by drawing the bow harder
across the strings.
ig
h
t
See how the piano can
produce quieter sounds
when I strike the piano
keys softly.
Solve this!
Look at the rubber bands
on the right. Which rubber
band will produce sounds
with a higher pitch? Circle.
W
C
op
yr
Watch the video
to see how a piano
works!
k
kboo
or
Worksheet 2
Sound
161
How can we tell and
compare the differences in
the sounds we hear?
Let’s investigate!
3
Lt
d
mpare the pitch and
co
to
e
al
sc
g
in
nk
ra
a
Aim: To use
volume of sounds.
Pitch
3
4
5
6
7
8
9
Quiet
1
Loud
Low
2
3
4
5
6
7
8
9
10
High
ca
Your teacher will play a quiet sound and a loud sound. Label the volume of
the quiet sound as '1' and the volume of the loud sound as '10' on the scale
shown above.
du
2
10
on
2
ti
1
Volume
P
te
Instructions:
1 We can compare the pitch and volume of sounds using a ranking scale.
E
Now, your teacher will play another sound. Use the same scale to compare the
loudness of the sound.
What is the volume of this sound according to your scale? ______
Compare with your classmates. Do you have the same number? ______
A
Your teacher will now play a low-pitched sound. The pitch of this sound is '1'.
Your teacher will play a high-pitched sound. The pitch of this sound is '10'.
20
23
4
ls
to
n
3
Your teacher will now play another sound. Use the scale above to compare the
pitch of the sound.
What is the pitch of this sound according to your scale? _____
Compare with your classmates. Do you have the same number? _____
The teacher will play four different sounds now. Refer to your scales and
choose a number for the pitch and the volume of each sound. Record in the
table below.
C
op
yr
6
ig
h
t
5
Sound
1
2
3
4
162
Chapter 10
Volume
Pitch
Questions:
1 Do loud sounds always have high
pitches? ______
2 Are high-pitched sounds always
loud? ______
4
Let’s investigate!
Lt
d
.
make different sounds
to
ts
en
m
ru
st
in
nt
re
ffe
Aim: To create di
How do
a string instrument and
a percussion instrument
create sounds? What
materials can you
use to make these
instruments?
P
te
Materials:
Tin cans Metal spoons Plastic box
Cardboard box Elastic bands Beans
ti
on
Instructions:
1 Create a string or a percussion instrument using the materials provided.
Try playing your instrument. Make a loud sound and a quiet sound.
Compare your instrument with your classmates’ instruments.
Is there a difference in the sounds produced? ______
du
ca
2
Can your instrument make a high-pitched sound and a low-pitched sound?
______
How can you make changes to your instrument to produce sounds of
different pitches? Write your suggestions below.
Make changes to improve your instrument according to your suggestions.
Test your suggestions to see if they work!
yr
4
ig
h
t
20
23
A
ls
to
n
E
3
C
op
Questions:
When playing your instrument, what would you do to:
1 Change the loudness of the sounds
____________________________________________________________
2 Change the pitch of the sounds
____________________________________________________________
Sound
163
Science in context
Lt
d
Loud noises can affect humans and animals.
ca
ti
on
P
te
When birds are near loud sounds, they can get frightened easily. If there is
too much loud noise in the surroundings, birds may not be able to hear and
sense their predators to escape in time.
ls
to
n
E
du
We should avoid listening
to loud music on our
headphones.
Birds living in noisy cities
full of low-pitched noises
sing at a higher pitch so
that other birds can hear
their mating calls.
C
op
yr
ig
h
t
20
23
A
Listening to loud noises for a
long period of time can harm our
hearing and cause hearing loss.
Ships and human activities such as oil drilling can increase the
noise levels in oceans. The loud noises can harm the hearing
of marine animals. It also makes it difficult for animals like
whales and dolphins to hear and communicate with their kind.
164
Chapter 10
ti
on
P
te
Lt
d
At the airport runway, loud sounds are produced when aeroplanes take off
and land.
ls
to
n
E
du
ca
Earmuff
op
yr
ig
h
t
20
23
A
Airport workers protect their hearing
by wearing earplugs or earmuffs.
I am an architect. I design airport buildings to make
sure that the people in the buildings are not affected
by the loud sounds produced by aeroplanes
during takeoffs and landings. I do this by adding
soundproofing materials into the building structure.
Think-Pair-Share
C
What other problems do loud noises cause?
Clues
Soundproof – To make something in a way that less sound can travel through
Sound
165
Crack the case
Sound
Lt
d
is
needs
ti
on
A ___________ containing
particles to travel
P
te
Produced by
___________
travels
Liquids
Gases
ls
to
n
E
Solids
du
ca
can be
C
op
yr
ig
h
t
20
23
A
When an object ___________, it ___________ with the
surrounding air particles. This causes the air particles to
___________. The air particles ___________ with even more
air particles, causing them to ___________ too. These
vibrations travel in waves called ___________.
166
Chapter 10
When ______________ reach our ears, we hear the sound.
Volume
Can be ___________ or
___________
Lt
d
can be affected by
The way we play an instrument
Can be ___________ or
___________
P
te
Pitch
Hitting the drum
___________ or
___________ with the
drumsticks
on
such as
ca
ti
can be
affected by
du
E
A
___________ hard or softly
into a trumpet or clarinet
20
23
Thickness of the
string in a string
instrument
ls
to
n
Length of the
string in a string
instrument
Drawing the bow
___________ or softly on the
violin strings
(🗸).
What can Tim do to lower his volume? Tick
Change the wooden stick to a plastic stick.
Hit the drum harder.
Hit the drum more softly.
Hit the drum faster.
Hit the drum slower.
W
C
op
yr
ig
h
t
Striking ___________ or
softly on the piano keys
k
kboo
or
Consolidation worksheet
Sound
167
CHAPTER 11
Tim is preparing for a
school trip that will bring
him to a country in the
Southern Hemisphere. He
lives in a country in the
Northern Hemisphere.
He will be leaving for the
trip the next day. What
clothes should he prepare
for his school trip?
Lt
d
Earth and Satellites
20
23
A
ls
to
n
E
du
ca
ti
on
P
te
What clothes
should I pack?
ig
h
t
What Will I Learn
C
op
yr
Describe how the Earth orbits the Sun.
Describe how Earth's tilt causes seasons in different parts
of the Earth.
Describe what satellites are.
Describe Earth's atmosphere and identify gases found in it.
State that most water on Earth is not pure and contains
dissolved substances.
Describe the water cycle and its processes.
168
Chapter 11
What seaso
n is
Tim’s countr
y
experiencin
g
now?
What season
are countries
rn
in the Southe
ost
Hemisphere m
ncing
likely experie
now?
What is the likely
temperature of
the country Tim
is going to? Will
it be high or low?
How does Earth orbit the Sun?
1
Lt
d
The Sun, which is a star, is at the centre of the Solar System. There are
planets, moons, comets and asteroids orbiting the Sun. Our planet
Earth orbits the Sun.
Let’s investigate!
P
te
odel.
orbits the Sun using a m
h
rt
Ea
w
ho
e
or
pl
ex
To
Aim:
ca
ti
on
Instructions:
1 Get a classmate to represent the Sun, while you represent the Earth.
E
Anticlockwise
A
Model the Earth's orbit by following the path marked out by your
teacher. Move in an anticlockwise direction.
20
23
2
ls
to
n
Look! I am moving in the
direction that is opposite
to the movement of the
clock hands.
Plastic cone
du
Movement
of clock
hands
ig
h
t
Questions:
1 Describe the shape of the path marked out by your teacher.
____________________________________________________________
As you move around your friend, what do you observe about the
distance between your friend and you? You can use a measuring tape
to measure.
C
op
yr
2
There are points in the path where I am _____________ to my friend
and points in the path where I am _____________ from my friend.
3
What do your observations tell you about the distance between the
Earth and the Sun as the Earth orbits?
There are points in the Earth’s orbit where the Earth is _____________
to the Sun and there are points in the Earth’s orbit where the Earth is
_____________ from the Sun.
Earth and Satellites
169
Lt
d
te
ti
on
P
Earth orbits the Sun in an anticlockwise direction. The orbit has an oval-like
shape, called an ellipse. But, it is not perfectly elliptical. That is why we say the
orbit has a shape of a slight ellipse. At some points in its orbit, the Earth is
closer to the Sun. At other points in its orbit, the Earth is further from the Sun.
ca
Think-Pair-Share
du
Do other objects in the Solar System orbit the Sun in a slightly elliptical path like the Earth? Do
they move in an anticlockwise direction around the Sun? Research and share your findings
with your classmates.
ls
to
n
E
It takes the Earth 365 and a quarter days to orbit the Sun.
This is called a year.
Four quarter
days make up
one full day!
I thought there were only 365
days in our calendar. Where is
the quarter day?
ig
h
t
What causes the different seasons?
23.5°
C
op
yr
The Earth spins on an axis that is tilted
at about 23.5 degrees. Due to this tilt, the
amount of sunlight that each location
on Earth receives is different throughout
the year. The amount of sunlight
received affects the temperature of the
location. So, temperatures at different South
Pole
parts of Earth will be different.
Axis
Clues
170
Chapter 11
Ellipse - An oval shape or a circle that has been flattened
North
Pole
W
20
23
A
To make up for the quarter day in a year, the quarter day is
counted and added to the calendar as an extra day once every
four years. So, February 29th is added to the calendar every four
years in a leap year. We have 366 days instead of 365 days in a
leap year.
k
kboo
or
Worksheet 1
Retrace our steps
What causes day and
night? How long does
the Earth take to spin
once on its own axis?
Let’s investigate!
2
Stickers Lamp
te
Materials:
Globe Lt
d
different parts of Earth
w
ho
t
ou
d
fin
to
el
od
m
ar.
Aim: Use a
different times of the ye
at
s
re
tu
ra
pe
m
te
nt
re
experience diffe
on
P
Instructions:
1 Paste the stickers labelled A, B and C on the globe. Place the globe and the
lamp on the table according to the diagram below.
2
Turn off all the other lights
in the room. This lamp on
the table represents the
Sun. At Position 1, which
location (A or B) has
more light shining on it?
________
3
Now, move the globe in an anticlockwise direction around the lamp in a
slight ellipse shape. As you move the globe, observe the amount of light
shining on locations A, B and C.
4
M
ove the globe around the lamp once more while rotating it about its own
axis to model day and night.
20
23
A
ls
to
n
E
du
ca
ti
Position 1
yr
ig
h
t
Questions:
1 When a location is tilted towards the Sun, does it receive more or less
sunlight? _____________________________________________________
2 If a location on Earth receives more sunlight, will it be colder or warmer?
_____________________________________________________________
C
op
Conclusions:
If the pole of the Earth is tilted towards the Sun, places located in this polar
region receive _____________ sunlight and are _____________.
If the pole of the Earth is tilted away from the Sun, places located in this polar
region receive _____________ sunlight and are _____________.
Places that are located near or in the middle of the Earth receive the
_____________ amount of light throughout the year. It is generally
_____________ throughout the year.
Earth and Satellites
171
Different seasons on Earth
Lt
d
It is summer in
the Northern
Hemisphere now.
It is so hot!
ca
ti
on
Summer
Northern Hemisphere and
Southern Hemisphere
E
ls
to
n
South
20
23
A
The lower half of
the Earth is called
the Southern
Hemisphere.
It is winter in
the Southern
Hemisphere now.
It is so cold!
C
op
yr
ig
h
t
In June, the Southern
Hemisphere is tilted away
from the Sun. Places here
receive less direct sunlight and
experience days with shorter
daytime. With less heat from
the Sun, the temperature in the
Southern Hemisphere is lower.
These places will experience
winter during this time of
the year.
The upper half of
the Earth is called
the Northern
Hemisphere.
du
North
In June, the Northern
Hemisphere is tilted towards
the Sun. Places here receive
more direct sunlight and
experience days with longer
daytime. With more heat from
the Sun, the temperature in
the Northern Hemisphere
is higher. These places will
experience summer during
this time of the year.
P
te
The Equator
The imaginary line around the middle
of the Earth, called the Equator,
divides Earth into two halves called
the Northern Hemisphere and the
Southern Hemisphere. Some places
in the Northern Hemisphere and
Southern Hemisphere experience
four seasons — spring, summer,
autumn and winter.
172
Chapter 11
Winter
Spring
When Ada is
experiencing spring in the
Northern Hemisphere, it is
autumn here in the Southern
Hemisphere. The temperature
becomes lower and it can
get windy and rainy!
Lt
d
It is spring in the
Northern
Hemisphere now.
As the temperature
becomes higher,
we can see plants
growing and flowers
blooming!
te
P
Autumn
ti
on
Spring
In March, the
Northern
Hemisphere
experiences spring
while the Southern
Hemisphere
experiences
autumn.
In September, the Northern
Hemisphere experiences
autumn while the Southern
Hemisphere experiences spring.
Near the Equator
Places nearer to the Equator receive
the same amount of sunlight and heat
all year round. As such, these places
do not experience the four seasons
and it is usually warm all year round.
Think-Pair-Share
Which places on Earth
have different seasons?
What are spring, summer,
autumn and winter like?
W
C
op
yr
ig
h
t
Autumn
In December, the Northern
Hemisphere is tilted away from
the Sun and experiences winter.
The Southern Hemisphere
is tilted towards the Sun and
experiences summer.
Summer
20
23
A
ls
to
n
E
du
ca
Winter
k
kboo
or
Worksheet 2
Earth and Satellites
173
What are satellites?
te
Lt
d
A satellite is an object in space that orbits a larger object such as another
planet or star. As Earth orbits the Sun, Earth is also called a satellite. Satellites
can be artificial or natural. Natural satellites are objects in space that orbit a
planet or star. Earth is the natural satellite of the Sun.
on
P
Moon
Can you name
other natural
satellites that orbit
a planet or the Sun?
ls
to
n
E
du
ca
ti
The Moon is a natural satellite
that orbits a planet. Planets,
moons and asteroids which
orbit the Sun are examples of
natural satellites.
Artificial satellite
that orbits Earth
Artificial satellite
that orbits the Sun
C
op
yr
ig
h
t
20
23
A
Artificial satellites are objects launched into space to orbit
the Earth and other planets. These satellites collect and send
information back to the Earth. They are also able to take
pictures of the Sun and other planets.
174
Chapter 11
Artificial satellites can be used for telecommunication.
They receive signals from one location on Earth and
transmit signals to another location on Earth.
Lt
d
The International Space Station (ISS) is a large artificial satellite that orbits
the Earth. It is the home where astronauts live in when they are carrying out
experiments in space.
on
P
te
How are the conditions
in the outer space
different from the
conditions on Earth?
There is no air and water in space.
Hence, astronauts have to wear
special suits and live in places such
as the ISS.
du
ca
ti
The ISS
A
ls
to
n
E
What makes up Earth's atmosphere?
Earth's atmosphere
The layer of air surrounding the Earth
is called the Earth's atmosphere. Air
in the atmosphere is a mixture of
different gases.
20
23
Think-Pair-Share
ig
h
t
What are the gases that make up Earth’s atmosphere? What do we
use them for? What percentage of the atmosphere does each gas take
up? Using information from books or the Internet, research and present
your findings in a pie chart and a table.
Earth is the only planet that living things can live on. Earth provides us with
valuable resources such as air and water. Without clean air to breathe or
clean water to drink, we cannot survive.
W
C
op
yr
The Earth’s atmosphere is mainly made up of nitrogen gas and oxygen gas.
The remaining gases are mostly carbon dioxide, argon, water vapour and
other gases.
k
kboo
or
Worksheet 3
Earth and Satellites
175
Solve this!
The Northern Hemisphere is experiencing winter now.
a Draw to show the position of the Earth and
the Sun during this time.
Lt
d
1
What season is the Southern Hemisphere experiencing at this time of
the year? Explain your answer.
_____________________________________________________________
te
b
P
_____________________________________________________________
Which hemisphere will experience a longer length of daytime?
_____________________________________________________________
ti
on
c
Name two satellites that orbit the Sun and two satellites that orbit the Earth.
________________________________________________________________
3
The Earth is surrounded by a layer of air called the _____________________.
ls
to
n
Where can we find water on Earth?
E
du
ca
2
20
23
A
More than 70% of the Earth’s surface is covered with water.
Most of the water can be found in oceans, seas, rivers and lakes.
Water also exists in the atmosphere as water vapour. Water can
be found frozen in ice caps too.
Water moves around the Earth continuously and changes from
one state to another. Water moves around the Earth in a cycle
known as the water cycle.
Let ’s investigate!
ig
h
t
3
yr
Aim: To use a model to find out the processes involved in the water cycle.
C
op
Materials:
Transparent container with lid
Pack of ice
Sand Water
Table lamp
Instructions:
1 Fill one side of the container with sand. Pour some water on the other side of
the container.
176
Chapter 11
We can also use
warm water instead of
heating the water with
the lamp!
Lt
d
Pack of ice Lamp
Water
te
Cover the container with a
Lid
lid and place a pack of ice
on the lid.
Container
3 Using a lamp, shine light at
the water to heat it.
Observe what happens
after two hours.
Sand
2
ti
What is formed on the underside of the lid after two hours? Name the
process that causes this to occur. ___________________________________
ca
2
on
P
Questions:
1 What do the lamp, water and sand in the model represent?
_________________________________________________________________
E
du
Water moves around the Earth using three main processes — evaporation,
condensation and precipitation.
20
23
A
ls
to
n
Condensation
Water vapour loses energy to the cold air
and condenses to form tiny water droplets.
This process is called condensation. The tiny
water droplets gather and form clouds.
Evaporation
The Sun heats up water on the surface of the
Earth. Water particles gain energy from the
Sun. There is a change in state from liquid
to gas. This process is called evaporation.
Water vapour rises up into the sky.
C
op
yr
ig
h
t
Precipitation
When the water droplets in the clouds
get bigger and become too heavy to
stay in the clouds, they fall as rain. This
process is called precipitation.
Solve this!
Name and describe the process in the water cycle that forms clouds.
Earth and Satellites
177
Are all types of water on Earth pure?
Let’s investigate!
4
te
Shallow dishes
P
Materials:
Different types of water such as rainwater,
seawater, river water, tap water and distilled water
Lt
d
re.
of water on Earth are pu
s
pe
ty
l
al
if
t
ou
d
fin
d
Aim: To explore an
A
ls
to
n
E
du
ca
ti
on
Instructions:
1 Pour an equal amount of each type of water into a dish.
2 Observe the water in each dish. Which water looks transparent? Do you
think there are any substances dissolved in it?
3 Leave the dishes of water under the Sun for a day. Predict what will be left in
each dish after all the water has evaporated. Record your observations in
a table.
Can we drink
saltwater without
processing it?
C
op
yr
ig
h
t
20
23
Land
Most of the water on Earth can be
Freshwater
found in the ocean as saltwater.
in lakes
and rivers
The remaining water that is
available is freshwater. Most of
the freshwater is frozen in ice
caps and only a small portion
Freshwater
of freshwater is found in lakes
frozen in ice caps
and rivers.
Saltwater in
Clues
178
Chapter 11
oceans
Most of the water found on Earth is not pure. Freshwater
from lakes and rivers may be contaminated with sand, mud,
dissolved substances or things that can cause diseases.
As such, the water may not be safe for drinking.
Contaminated - Made dirty or not pure
Lt
d
Water that looks clear may contain some
dissolved substances such as minerals and
salts. It is not pure as well.
If solids are left behind after
water has evaporated, this
shows that the water is not
pure.
P
te
Water from a tap looks clear and
transparent. Do you think it is pure?
on
To obtain pure water, we can filter and process water in scientific laboratories.
Watch out!
ti
ca
du
In some places, water is treated before it flows to
the tap. So, it is safe to drink directly from the tap
in these places. However, not all places treat water
before sending it to the tap. It may not be safe to
drink directly from the tap in these other places.
W
20
23
A
Is it safe to drink
from the tap?
ls
to
n
E
Drinking water, such as bottled water, has been
treated to remove harmful substances. Some
dissolved substances such as minerals that
are good for our health are kept in this type of
water. It is clean and safe for us to drink. So, clean
water is different from pure water because it still
contains some dissolved substances.
The water in this
bottle is not pure.
Can I drink it?
k
kboo
or
Worksheet 4
Science in context
C
op
yr
ig
h
t
It is important for a country to have access to clean
water for drinking. Research on the Internet to find
out how water is treated in your country. Draw a
poster to show the steps involved.
In places where people do not have access to water,
technology such as a fog net can be used to harvest
water for watering crops. Fog nets help to trap fog
which is collected as water in the containers under
the net.
Clues
Watch the
video to find
out how the
fog net works!
Fog - Tiny water droplets that can form clouds near Earth's surface or around
mountains that can make it hard for us to see through
Earth and Satellites
179
Crack the case
Takes ____________ and
Sun
____________ days to orbit the
Orbits the Sun in an ____________
direction in a slight ____________ path
on
P
is
Covered mostly in _______
which is mostly not _______ and
contains dissolved substances
ca
ti
Spins on an axis that is _______
at about 23.5°
E
ls
to
n
A
which
create
du
so
Amount of sunlight and
temperature are different at
different parts of Earth
te
Lt
d
Earth
Water moves continuously
around Earth in the water
cycle through processes —
___________, ___________
and ___________
ig
h
t
Autumn
20
23
Different seasons
C
op
yr
Spring
180
Summer
If the hemisphere is tilted _________ the Sun,
places there will receive ___________ sunlight and
experience days with _________ daytime.
These places will experience summer.
Winter
If the hemisphere is tilted ___________ from the
Sun, places there will receive ___________ sunlight
and experience days with _________ daytime.
These places will experience winter.
Chapter 11
ch contains air with gases
Surrounded by a layer of ____________ whi
_____ and
such as n_______, o_______, c_______ d__
w_______ v_______
te
Lt
d
is
on
An object in space that _______
a larger object
ca
ti
Satellite
which is
P
is a
E
_____________
Artificial
such as
International Space
Station (ISS)
ig
h
t
20
23
_____________
A
such as
ls
to
n
Natural
du
can be
country he is
e should prepare summer clothes as the
H
going to will be experiencing summer.
W
C
op
yr
ool trip? Tick (🗸).
What clothes should Tim prepare for his sch
ntry he is
He should prepare winter clothes as the cou
going to will be experiencing winter.
k
kboo
or
Consolidation worksheet
Earth and Satellites
181
CHAPTER 12
Pollution
Lt
d
I have not been feeling well
living here. My neighbourhood
used to be very quiet.
du
I cannot even see what
is in front of me clearly
when I am outside the
house! What can I do?
ig
h
t
20
23
A
ls
to
n
E
Now, it is so crowded
and noisy. I no longer like
my surroundings. I have
been coughing more and
more recently.
ca
ti
on
P
te
How are you? It has
been very cold this
week! Brrr...
C
op
yr
What Will I Learn
182
✓ Describe what pollution is.
✓ Identify types of pollution and give examples.
What has
changed over
the years in Tim’s
neighbourhood?
Chapter 12
using
What is ca
gh?
Tim to cou
s the
Where doe
e from?
cause com
What is making
it difficult for Tim
to see the things
around him? Where
does it come from?
What is pollution?
Living things need clean air, water and food to thrive and reproduce.
Lt
d
Think-Pair-Share
If air, water and food are not clean, how will it affect living things? Discuss with your
classmates.
ti
on
P
te
However, the quality of air, water and food can be affected when
humans introduce substances that harm the environment. This is
called pollution. The harmful substances that are produced from
human activities are called man-made pollutants. Pollutants affect the
environment and the health of living things negatively.
A
ls
to
n
E
du
ca
There are three main types of pollution — land pollution, water pollution
and air pollution.
Water pollution
C
op
yr
ig
h
t
20
23
Land pollution
Air pollution
Think-Pair-Share
Using the Internet or books, research to find out more about a type of pollution. You may
use the guiding questions below.
Guiding questions:
1 What are the pollutants that cause this pollution?
2 What effects does this pollution have on living things?
Use a poster to present your findings to your classmates.
Pollution
183
What is land pollution?
Land pollution occurs when waste materials are dumped on land and these
materials release harmful chemicals that contaminate the soil.
te
Lt
d
Land pollution can be caused by landfills. The rubbish we throw usually ends
up in landfills. Factories may also get rid of their chemical wastes in landfills.
P
Objects made of
materials like plastic
and glass take very
long to break down, so
they stay on Earth for a
very long time!
ls
to
n
A
We bring the waste
to the recycling plant.
The recycling plant
converts the waste into
new, clean and usable
materials.
We can reuse items instead
of throwing them away.
For example, we can use
aluminium cans to grow plants.
C
op
yr
ig
h
t
20
23
We can help to recycle
waste by sorting and
throwing our trash into the
correct recycling bins. Look
out for the recycling symbol
on the items used. It tells us
if the item is recyclable.
E
du
ca
ti
on
We are running
out of space to bury
our rubbish before
it gets broken down!
We should try to
reduce our waste by
buying only what we
need.
Look around you,
which objects are
made of recyclable
materials?
Water supply wells
184
Chapter 12
We should reduce the use
of chemical pesticides to
prevent contaminating the
waters! We can use natural
fertilisers.
Lt
d
Land pollution can also be caused by the use of chemical
fertilisers and pesticides. These chemicals are poisonous
and overusing them may kill animals living on the farm.
ca
ti
on
P
te
Chemicals in pesticides
or fertilisers are toxic. It
is harmful to breathe in
these chemicals.
E
du
To see how harmful chemicals can
get into plants, try placing a cut piece
of celery stem in a beaker of water
with food colouring. What do you
observe in the stem?
ls
to
n
Think-Pair-Share
If the food colouring in the water represents harmful chemicals in the groundwater, what do you
think will happen to a plant growing in soil that takes in groundwater containing harmful chemicals?
20
23
A
What happens if chemicals from land pollution contaminate soil with plants growing on them?
What happens if we eat these plants?
River
Groundwater
Clues
Harmful chemicals
W
C
op
yr
ig
h
t
Harmful chemicals released into the soil can enter the
groundwater. We use groundwater for drinking and farming.
Drinking contaminated water or eating food grown with
contaminated water can harm our health. Contaminated water
may also affect plant health and cause the plants to die.
Harmful chemicals in the groundwater can enter rivers and
lakes, causing water pollution.
k
kboo
or
Worksheet 1
Groundwater – Water found below the surface of the Earth, occupying the spaces in
soil and in between rocks and sand
Pollution
185
What is water pollution?
Lt
d
Water pollution can occur when harmful substances
such as sewage, microplastics, oil and toxic chemicals
contaminate water sources. We can pollute the
water too if we do not get rid of our waste properly.
ls
to
n
E
du
ca
ti
on
P
te
Microplastics are found in some facial cleansers
and toothpastes. When we wash clothes made
of plastic, loose threads that get washed off
the clothes are microplastics as well. When
we use these products or wash these clothes,
microplastics get washed into the wastewater,
down the drain pipes and into the water bodies.
Microbeads in some toothpastes and facial cleansers are microplastics.
Think-Pair-Share
A
Look at the objects around your house. Are there objects that contain microplastics?
These microplastics may be eaten by
animals living in the water and cause
harm to their health.
yr
ig
h
t
20
23
We should get rid of
our waste properly.
We should not litter!
C
op
Animals may mistake waste or
litter in the water for food. Many
underwater animals die after
eating them. Some litter may
also injure marine animals.
Clues
186
Chapter 12
Plastic waste in water can also break down
into smaller pieces over time. Eventually, they
may become tiny microplastics.
Microplastics – Very small pieces of plastic that are found in household products or
broken down from larger plastic objects
We try to reduce the
use of chemicals and
pesticides on the
farm.
Lt
d
Factories may release toxic
chemicals and oil into rivers
or lakes nearby.
P
te
Toxic chemicals and pesticides used by farmers can
contaminate groundwater. These toxic substances
can get washed into rivers and lakes.
ti
on
Bring your own
reusable shopping bags when
you go shopping. This reduces the
amount of plastic being dumped
into the water.
We should sort and dispose
of our waste properly into
the correct recycling bins.
ls
to
n
E
du
ca
Microplastics are too
small to be filtered
by the wastewater
treatment plants.
A
Oils from the ship or tanker may spill into
the sea when an accident occurs. Oil from
the spills may stick to sea animals.
This water is
polluted! It is not
safe to drink!
W
C
op
yr
ig
h
t
20
23
Feathers of seabirds may
get coated with oil. They
cannot fly properly, causing
them to have problems
obtaining food and escaping
from danger.
k
kboo
or
Worksheet 2
Polluted water becomes murky, blocking sunlight from
reaching underwater plants. Plants living in water may die
as there is not enough sunlight for them to make food.
Pollution
187
What is air pollution?
Air pollution occurs when harmful gases, chemicals and smoke are
introduced into the air and atmosphere.
ti
on
P
te
Sometimes, farmers burn trees and plants to clear the land quickly for
farming. During burning, a lot of pollutants are released into the air.
Lt
d
When we burn fossil fuels in vehicles or power stations, carbon dioxide and
other harmful gases are released into the air.
We should use renewable
sources of energy instead of
burning fossil fuels.
We should switch
off electrical appliances
when they are not in use. This
helps save electricity which
will help to cut down the
burning of fossil fuels.
C
op
yr
ig
h
t
20
23
A
ls
to
n
E
du
ca
Hot and dry weather
conditions can sometimes
cause forest fires!
188
Harmful
gases in the air can
cause heart and lung
diseases.
Chapter 12
Sometimes, air pollution
can make it difficult for
us to see things that are
far away from us!
Solar
panels
Watch out!
Are all pollutants man-made?
Lt
d
In nature, harmful gases and ash can be produced from volcanic
eruptions and forest fires. These substances are called natural
pollutants as they are not produced by human activities.
du
ca
ti
on
P
te
The harmful gases released into the air can react with water and oxygen to
form acid. The acid mixes with water droplets in the clouds. When the clouds
get too heavy, the water droplets and the acid fall to the ground as acid rain.
A
ls
to
n
E
Effects of acid rain on buildings and plants
Acid rain can also damage buildings
and structures.
C
op
yr
ig
h
t
20
23
To reduce air pollution,
we should take public
transport. A public bus can
carry more passengers than a
car. This reduces the number
of cars on the road.
Acid rain kills plants which are food
producers. When plants die, food
supply for animals in the food chain
is affected.
When acid rain gets into rivers and seas, it can
kill animals and plants living in the water.
Pollution
189
Let’s investigate!
1
e effect of
Aim: To find out about th
.
acid rain on plant health
Lemon juice is a
type of acid.
Lemon juice
du
ca
ti
Water
on
P
te
Lt
d
Materials:
Water Lemon juice Ruler
Six small potted plants of the same type and height
Measuring cylinder
Group A
Group B
yr
ig
h
t
20
23
A
ls
to
n
E
Instructions:
1 Place the pots of plants near a window. Split them into Group A and Group B
according to the diagram above.
2 Water each plant in Group A with 20 ml of water daily. Water each plant in
Group B with 20 ml of lemon juice daily. Observe the health and the growth
of the plants after a week. Take note of the colour of the leaves and the
appearance of the stem.
3 Using a ruler, measure the height of each plant daily. Draw a table and
record your findings.
C
op
Question:
Which group of plants looks unhealthier after a week? ____________
Conclusion:
Just like lemon juice, acid rain contains acid too. What can your results tell us
about the effect of acid rain on plant health?
__________________________________________________________________
190
Chapter 12
How can pollution occur on a global and local scale?
Pollution can be devastating because its effects can become widespread.
P
te
Lt
d
Air pollutants
can be carried and
move easily in the
air. They can spread
to many areas or
countries!
ca
ti
on
Air pollution can
occur on a global scale if
there are large amounts
of air pollutants in the
Earth’s atmosphere. This
means that the entire
planet can be affected!
More heat is
trapped in
the Earth’s
atmosphere
Earth's surface
ls
to
n
E
du
Trapped heat
in the Earth’s
atmosphere
Due to pollution, the amount of carbon
dioxide and other gases in the atmosphere
has been increasing. This causes more
heat to be trapped in Earth's atmosphere.
20
23
A
Carbon dioxide and other gases in the
atmosphere trap heat from the Sun. This
helps to keep the Earth warm.
Earth's surface
HELP!
Pollution can
occur on a local scale
as well. For example,
land pollution caused
by landfills may only
contaminate soil
near the landfills.
Global warming can cause polar ice caps on
Earth to melt more quickly. This can cause the
sea level to rise. As the sea level rises, low-lying
areas may be flooded.
W
C
op
yr
ig
h
t
Pollution causes more heat to be trapped on Earth and our planet becomes
warmer. This results in global warming which can affect the entire Earth.
Clues
k
kboo
or
Worksheet 3
Devastating – Causing a lot of damage or harm
Pollution
191
Think-Pair-Share
What other types of pollution are there?
What effects do these
types of pollution have on
us and other living things?
te
Lt
d
Other than land,
water and air pollution, what
other types of pollution
are there?
What are some
other ways to reduce the impact
of pollution on our planet? Research
or interview an environmental
scientist to find out!
on
P
Science in context
ls
to
n
E
du
ca
ti
I am an environmental
scientist. I collect samples
from the environment and
carry out experiments to
identify the pollutants in
them. I also think of ways
to prevent and manage
environmental problems
caused by pollution.
Solve this!
Watch the video to learn
about a day in the life of an
environmental scientist.
Fill in the blanks.
_______________ occurs when humans introduce substances which are
harmful to the _______________ . These harmful substances are called
_______________ .
2 Name the correct type of pollution.
op
yr
ig
h
t
20
23
A
1
C
3
192
Tick (🗸) the correct solution to each type of pollution.
Type of pollution
Solution
Air pollution
Use electricity generated from renewable sources of energy
Land pollution
Reduce the use of chemical pesticides and fertilisers in farming
Water pollution
Switch off electrical appliances when they are not in use
Chapter 12
Correct?
Crack the case
caused by
Pollution
Lt
d
Harmful ___________ pollutants
which are introduced by humans
into the environment
caused by
Water pollutants
Land pollutants
te
Air pollutants
include
can result in
on
ti
_______, ____________,
_________ and
__________________
____________________
dumped on land and
________________ used in
farming
ca
________________,
________________
and _________
P
include
include
du
can result in
Poor water quality
Underwater animals
and plants may die
ls
to
n
E
Acid rain
Heart and
lung diseases
Contaminated soil and
groundwater, causing harm
to the health of living things
can be reduced by
can be reduced by
C
op
yr
What can Tim do? Tick (🗸).
Tim can get an air purifier to help him
clean the polluted air in his house.
im should close all his windows
T
to keep out the noise from his
neighbourhood.
Tim should open all his windows to let
more fresh air in.
Tim should burn more firewood to
keep himself warm.
The poor air quality is making Tim
cough. He should wear a mask when
he is outside.
W
ig
h
t
20
23
A
can be reduced by
can result in
k
kboo
or
Consolidation worksheet
Pollution
193
Science keywords
Chapter 1
Page
Chapter 7
Page
chlorophyll, flower, flowering plants
4
attraction, magnet, repulsion
non-flowering plants
5
magnetic force, magnetic field
98
magnetic material
100
97
6
carpel, female, fruit, ovary, sepal, stigma, style
7
adult plant, seed, young plant
10
germination, leaves, root, shoot
11
reproduction, temperature
14
pollination
15
digestion, digestive system
fertilisation
16
mouth, oesophagus, stomach, teeth, tongue
118
anus, small intestine, large intestine, rectum
119
24
Chapter 3
Page
carbon dioxide, gas, gaseous,
hydrogen, liquid, nitrogen, oxygen,
matter, state, solid, water vapour
35
properties
38
energy, particle
41
te
P
Page
on
seed dispersal
Chapter 8
adequate diet
balanced diet
Chapter 9
water
47
melting point
50
freezing point, properties
A
51
expand
boiling point
evaporation, particle
condensation
Chapter 5
20
23
54
129
131
camouflage
134
Page
vibrate, vibrating source
151
particles, sound wave
154
medium
155
high, low, pitch
160
loud, quiet, volume
161
56
58
62
Page
Chapter 11
Page
Earth, orbit, Sun
169
anticlockwise, leap year,
slight ellipse, tilt, year
170
67
autumn, Equator, Northern Hemisphere,
seasons, Southern Hemisphere, spring,
summer, winter
172
properties
69
moon, planet, satellite
174
mixing
73
175
176
saturated
75
argon, atmosphere, carbon dioxide,
nitrogen, oxygen
yr
ig
h
t
dissolve, homogeneous, insoluble, soluble,
solute, solution, solvent
evaporation, irreversible, reversible
77
water cycle
Chapter 6
Page
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predator, prey
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Page
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122
adaptation, environment
Chapter 10
Chapter 4
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adaptation, environment, pollination,
pollinator
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magnetic strength
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temporary magnet
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Chapter 2
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anther, filament, male, petal, pollen grain,
stamen
condensation, evaporation, precipitation
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pure
178
gravity
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balanced, direction, normal force, size
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applied force, unbalanced
85
man-made pollutant, pollution
friction
87
land pollution
air resistance
184
89
water pollution
water resistance
186
90
air pollution
float, sink, upthrust
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93
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Science keywords
Chapter 12
Page
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Credits
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Let’s think and work like a scientist! — p.vi: Gustova Svetlana/Shutterstock.com (White flying dandelion); Sanneos/Shutterstock.com (Water hyacinth);
Scisetti Alfio/Shutterstock.com (Cactus); tkatasila/Shutterstock.com (Pine tree); Kseniia Perminova/Shutterstock.com (Branch of spruce tree)
Chapter 1 — p.4: Pasquale/Shutterstock.com (Flowers of tomato); Yuriy Korzhenevskyy/Shutterstock.com (Tomatoes); p.5: Makistock/Shutterstock.com
(Cherry blossom tree); Sai Tha/Shutterstock.com (Mango tree); Hanahstocks/Shutterstock.com (Moss); olivier Villard/Shutterstock.com (Fern); Chris
Redan/Shutterstock.com (Conifer); Jeff Holcombe/Shutterstock.com (Curly fern); vladdon/Shutterstock.com (Austrian pine); nadia_if/Shutterstock.com
(White beautiful flowers); p.7: Pozharskii Andrei/Shutterstock.com (Flower bud); p.8: Pelevina Ksinia/Shutterstock.com (White lily)
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Chapter 2 — p.21: agap/Shutterstock.com (Desert with joshua tree); Victor Potasyev/Shutterstock.com (Trees in snow); Erik Steinebach/Shutterstock.
com (Water pond); p.22: mashurov/Shutterstock.com (Tulips); p.25: Nonnakrit/Shutterstock.com (Coconut); Brian A Jackson/Shutterstock.com (Seeds
of dandelion); Irina Bg/Shutterstock.com (Pea); Shi Yali/Shutterstock.com (Mango fruit on tree); SakSa/Shutterstock.com (Acorn on tree); Philip George
Jones/Shutterstock.com (Goosegrass); p.28: grey_and/Shutterstock.com (Aluminium foil); StanislauV/Shutterstock.com (Coloured paper); Ekaterina43/
Shutterstock.com (Velcro tape); Anton Starikov/Shutterstock.com (Tape); p.29: COULANGES/Shutterstock.com (Seed of Javan cucumber); Sunter
phakkawat99/Shutterstock.com (Sharp spines on the cactus); Dragon Claws/Shutterstock.com (Barrel cactus); Studio Barcelona/Shutterstock.com
(Pancake prickly pear cactus); LHBLLC/Shutterstock.com (Saguaro cactus); p.30: Photoongraphy/Shutterstock.com (Aloe vera); Stefano Benanti/
Shutterstock.com (Water lily); Victoria Tucholka/Shutterstock.com (Water hyacinth with purple flower); Bilanol/Shutterstock.com (Amazing winter
landscape); Sestra/Shutterstock.com (Branches of spruce); p.31: judesmart1/Unsplash.com (Aloe vera); Irk_lig/Shutterstock.com (Coniferous trees);
Mahirov9/Shutterstock.com (Branch of a coniferous tree)
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Chapter 4 — p.47: Verina Marina Valerevna/Shutterstock.com (Snow-covered trees); tograff/Shutterstock.com (Ice surface with red boat); RnDmS/
Shutterstock.com (Lake); Anna Om/Shutterstock.com (Sailboat); p.48: Soonthorn Wongsaita/Shutterstock.com (Airplane); p.51: khwanchai/Shutterstock.
com (Melting ice cube on wooden table); Elena Berd (Icicles); p.54: Melissa King/Shutterstock.com (Iceberg in ocean); p.57: Carolyn Franks/Shutterstock.
com (Boiling pot of water); p.58: leungchopan/Shutterstock.com (Hot spring); p.63: Pascal Huot/Shutterstock.com (Condensation on window)
Chapter 5 — p.67: Svittlana/Shutterstock.com (White powder dissolved in water); Ihor Matsiievskyi/Shutterstock.com (Chemical beaker); Sylwia Brataniec/
Shutterstock.com (Red powder)
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Chapter 7 — p.122: BW Folsom/Shutterstock.com (Metal fork); All For You/Shutterstock.com (Metal clip); Winai Tepsuttinun/Shutterstock.com (Door keys);
KARTHIK SENNIYAPPPAN/Shutterstock.com (Gold bangles); grey_and/Shutterstock.com (Aluminium foil); Hayati Kayhan/Shutterstock.com (Marbles);
SmileStudio/Shutterstock.com (Wooden ruler); images and videos/Shutterstock.com (Copper wires); Billion Photos/Shutterstock.com (Water bottles)
Chapter 8 — p.122: ifong/Shutterstock.com (Food plate); p.123: robuart/Shutterstock.com (Nutrition facts)
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Chapter 9 — p.131: Danita Delimont/Shutterstock.com (Cheetah); Maggy Meyer/Shutterstock.com (Running Lion); p132: KGrif/Shutterstock.com (Hawk
flying); AlecTrusler2015/Shutterstock.com (Swallow); Suntisook.D/Shutterstock.com (Tiger claws); Vladimir Kogan Michael/Shutterstock.com (Osprey
catching fish); Lucasdm/Shutterstock.com (Close up of cheetah); Jolanda Aalbers/Shutterstock.com (Red European Fox); Matt_Williams/Shutterstock.
com (American Bald Eagle); p.133: marhus/Shutterstock.com (Raccoon); jadimages/Shutterstock.com (Great Horned Owl); Vasilev Evgenii/Shutterstock.
com (African Lion); PatP66/Shutterstock.com (Lion cubs walking); shivaram subramaniam/Shutterstock.com (Camouflaged snow leopard); p.134: John A.
Anderson/Shutterstock.com (Red scorpionfish); Luiz Antonio da Silva/Shutterstock.com (Toucan); kajornyot wildlife photography/Shutterstock.com (Male
Baya Weaver); marich/Shutterstock.com (Hawk with open beak); p.135: Vaclav Sebek/Shutterstock.com (Blue hummingbird); Joseph Scott Photography/
Shutterstock.com (Great Blue Heron fishing); Bill Roque/Shutterstock.com (Pelican bird); Rudmer Zwerver/Shutterstock.com (Puffin); p.136: Mara008/
Shutterstock.com (Zebra); Richard Constantinoff/Shutterstock.com (Tiger close up of face); photos martYmage/Shutterstock.com (Screaming macaque);
Okyela/Shutterstock.com (Male gorilla yawns); p.137: Montri Thipsorn/Shutterstock.com (Hoof); Jean Landry/Shutterstock.com (Fast running deer); Sergey
Uryadnikov/Shutterstock.com (Wildebeest migration); Gail Johnson/Shutterstock.com (Group of fish); teekayu/Shutterstock.com (Malayan porcupine);
p.138: Vittorio Bruno/Shutterstock.com (Octopus and black ink); Aries Sutanto/Shutterstock.com (Pufferfish); Dirk Ercken/Shutterstock.com (Poison dart
frog); Evoken/Shutterstock.com (Rabbit resting); Visionlabs/Shutterstock.com (Earthen frog); Mr. SUTTIPON YAKHAM/Shutterstock.com (Turtle); p.139:
Huaykwang/Shutterstock.com (Dead leaf butterfly); Muskoka Stock Photos/Shutterstock.com (Black chicken); Callipso/Shutterstock.com (Red horse);
Rudmer Zwerver/Shutterstock.com (Grey Wolf); Eivor Kuchta/Shutterstock.com (Male Bighorn Sheep); Frank Wasserfuehrer/Shutterstock.com (Male
Frigate Bird ); p.140: Laborant/Shutterstock.com (Camel side view); Anan Kaewkhammul/Shutterstock.com (Camel front); Macronatura.es/Shutterstock.
com (Desert beetle); p.141: Lyn Relph/Shutterstock.com (Cactus Wren); Alexandra Lande/Shutterstock.com (Camel); Rosa Jay/Shutterstock.com (Fennec
fox); Eric Isselee/Shutterstock.com (Cape Ground Squirrel); IELEWAUT/Shutterstock.com (Squirrel in the Namib desert); p.142: polarman/Shutterstock.com
(Ringed seal); p.143: Alexey Seafarer/Shutterstock.com (Polar bear); Elpisterra/Shutterstock.com (Paws of polar bear); Jim Cumming/Shutterstock.com
(Snowy owl); Glass and Nature/Shutterstock.com (Arctic fox); p.144: Vlad61/Shutterstock.com (Tropical fish and hard corals); Dany Kurniawan/Shutterstock.
com (Fish gills); p.145: bozmp/Shutterstock.com (Humpback whale); Imagine Earth Photography/Shutterstock.com (Humpback whales); chonlasub
woravichan/Shutterstock.com (Coral reef); Sagittarius Pro/Shutterstock.com (Underwater background); p.146: Denis Burdin/Shutterstock.com (Ices and
icebergs); Kenneth Keifer/Shutterstock.com (Desert); yanik88/Shutterstock.com (Snow covered mountain peaks); svrid79/Shutterstock.com (Beluga
whale); Natalia Paklina/Shutterstock.com (Reindeer); Been there YB/Shutterstock.com (Desert kangaroo rat); p. 148: taviphoto/Shutterstock.com (Male
red deer)
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Chapter 10 — p.151: Chromakey/Shutterstock.com (Clarinet); Vereshchagin Dmitry/Shutterstock.com (Trumpet); RemarkEliza/Shutterstock.com (Guitar);
elenovsky/Shutterstock.com (Red drum); AGCuesta/Shutterstock.com (Violin); p.152: Matva/Shutterstock.com (Girl playing the violin); LightField Studios/
Shutterstock.com (Man playing guitar); kazuya goto/Shutterstock.com (Girl playing trumpet); west_photo/Shutterstock.com (Woman playing clarinet);
Ricardo Alves 1975/Shutterstock.com (Boy playing drum); Peter Horrox/Shutterstock.com (Brass metal gong)
Chapter 11 — p.170: Sahara Prince/Shutterstock.com (Earth); p.176: ixpert/Shutterstock.com (Earth water surface); p.178: Dr Morley Read/Shutterstock.com
(Brown water with sediment); p.179: Elena Elisseeva/Shutterstock.com (Filling a glass of water)
Chapter 12 — p.183: Nattaret Dechakanee/Shutterstock.com (Land with garbage); s0urav_diaz/Shutterstock.com (Water pollution); aapsky/Shutterstock.
com (Air pollution); p.184: mspoli/Shutterstock.com (Group of recycled cans); p.186: Alexandr Makarov/Shutterstock.com (Toothbrush with toothpaste);
KYTan/Shutterstock.com (Bottles of lotion containing microplastics); IgnacioFPV/Shutterstock.com (Microplastic fibres); p.189: Chris Hellyar/Shutterstock.
com (Acid rain damage); Axel Jung/Shutterstock.com (Forest damaged by acid rain); p.192: MikeDotta/Shutterstock.com (Landfill); Maksym Gorpenyuk/
Shutterstock.com (Water pollution of Bagmati River); NadyGinzburg/Shutterstock.com (Pollution from the exhaust of cars)
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Textbook
Workbook
Teacher’s Guide
Digital Textbook, Workbook,
and Teacher’s Guide
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The series
consists of:
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To encourage problem-based learning (PBL), each
chapter starts with a case problem. In each chapter,
learners will explore anchor investigation activities and
Learners will also learn how to apply scientific knowledge
to the real world in Science in Context. With greater
involvement in their learning, learners are challenged
to think critically, reason logically and become effective
problem solvers. They will also develop a love for science
as they recognise its importance and relevance in their
daily lives.
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Learners will investigate science strands like Biology,
Chemistry, Physics and Earth and Space. Learners are
also taught to Think and Work Scientifically, which
develops learners’ scientific enquiry skills and practical
skills.
hold discussions that precede the teaching of every key
concept. Learners will need to collaborate with their
peers, infer concepts and draw conclusions. Learners
will solve the case by the end of the chapter. This is
supplemented by colourful illustrations and easy-toread explanations to solidify their understanding. Wellcrafted exercises at various learning points help learners
to assess their learning and build process skills.
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Active Science
The series is developed
to comprehensively cover all the learning objectives of
the Cambridge Primary Science curriculum framework
(0097). The series adopts an Active Learning approach,
which allows learners to actively build their own
understanding through exploration, discussion and
problem-solving.
• Downloadable resources for teachers,
including printables for hands-on activities, worksheets and
test papers.