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Hi there,
Glad you downloaded this free Ebook.
After reading this book, you are one step closer to conquering
the explain-type questions in science exams.
How to use this guidebook:
1) There are 13 MUST KNOW concepts.
2) Remember the underlined key words in each concept.
3) Apply the keywords in your open-ended questions.
4) For explaining and describing science concepts, I have
provided the sentence structure to write the answers clearly.
Apply them in your exams.
To the kids:
I understand your parents might have forced you to read
through this so I have kept this short for your easy reading.
Read the scientific thinking process behind each question.
You need to spot the clues and link them to the correct science
concepts.
Take this book as a supplementary reading material before
entering the exam.
Note:
Do not use this ebook with a “must fit all the words into the
question” approach.
The phrase/sentence MUST answer the question.
Happy reading!
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Table of contents
Must Know Heat and Temperature Concepts ...........................- 1 Must Know Evaporation and Condensation Concepts..............- 6 Must Know Three states of matter Concept ...........................- 13 Must Know Reproduction in plants Concept ..........................- 16 Must Know Light and shadows Concept .................................- 18 Must Know Digestion Concepts ...............................................- 19 Must Know Circulatory System Concepts................................- 20 Must Know Food Chains and Food Web Concepts .................- 21 Must Know Electricity Concepts ..............................................- 22 Must Know Brightness of Bulbs Concept ................................- 25 Must Know Electromagnetic Concepts ....................................- 27 Must Know Forces Concepts ....................................................- 29 Must Know Energy Concepts ...................................................- 30 About the Author .....................................................................- 31 To All Concern Parents .............................................................- 32 You Might Be Interested In These ...........................................- 33 -
ScienceShifu.com
Must Know Heat and Temperature Concepts
Explain the heat flow process
1) Object 1 gains/loses heat to object 2
Example: The iron rod gains heat from the candle
flame.
OR
The glass rod loses heat to the surrounding air.
Explain why an object is hotter than the other object
(with changes in temperature shown)
2) Object 1 has a higher temperature than object 2.
Example: Water has a higher temperature than air.
Result: Water is hotter than air.
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Explain why an object is not hot after applying heat.
3) Poor conductor of heat gains/loses heat slowly
Example: Glass is a poor conductor of heat and takes
in heat slowly.
Result: Temperature of glass does not rise a lot.
Explain why an object turns hot quickly after applying
heat
4) Good conductor of heat gains/loses heat quickly
Example: As steel cup is a good conductor of heat and
takes in heat quickly.
Result: The temperature of steel cup rises a lot.
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Combining Concepts 1 to 4
Steel
plate
Glass plate
Both plates are placed in the fridge for a few hours.
Mary then take them out and touch the two plates.
Explain why her hand feels colder when she touches
the steel plate.
Scientific thinking process:
The question is showing different materials.
This means question wants you to use the science
concepts 3 and 4: Good and poor conductors of heat.
Also, the question mentions Mary hands feel colder
when she touches the metal plate.
Question wants you to use concepts 1 and 2: Heat flow
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Answer:
Concept:
Steel is a better conductor of heat than glass.
Explanation:
The steel gains heat from Mary’s hands faster than
glass.
OR
Mary’s hand loses heat faster to the steel plate than
the glass plate.
End result:
Mary’s hands will feel colder when she touches the
steel plate.
Object expands and contracts
5) The object gains heat and expands on a hot day.
Note: It is recommended to use the complete phrase
as underlined.
6) The object loses heat and contracts on a cold day.
Note: It is recommended to use the complete phrase
as underlined.
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Identify Concept 5 or Concept 6
The diagram below shows a steel rod before heating up.
Before heating
Original length of the steel rod: 15cm
The steel rod is heated and the length of the steel rod is
measured.
After heating
Length of the steel rod after heating: 17cm
Scientific thinking process:
Question has given you clues.
The length of the steel rod increases after heating up.
You should use the correct science concept: Concept 5
Explain why did the final length of the steel rod increase after
heating?
When the steel rod is heated up, the steel rod gains heat and
expands.
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Must Know Evaporation and Condensation Concepts
Factors affecting rate of evaporation
7) Exposed surface area to surrounding air.
Take note: Water cannot evaporate when there is no
exposed surface area.
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Layer of oil
300ml of
Water
Apply concept 7
Setup A
Setup B
300ml of
Water
Both setup A and B are placed in room beside the
window for 3 hours.
Mary observed the amount of water in setup B
decreases to 230ml whereas the amount of water in
setup A remains the same. Explain Mary’s
observation.
Scientific thinking process:
See the clues in the diagram: Setup A has layer of oil and
Setup B does not.
Also, the question mentions amount of water has
decreased. This means there is evaporation of water.
After analysing the clues, which science concept can be
used to answer this question?
Concept 7: Exposed surface area.
There is a layer of oil in setup A. There is no exposed
surface area for water to evaporate into water vapour
in setup A.
Result: water will not evaporate in setup A.
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8) Higher temperature of the liquid will increase rate of
evaporation.
Combining concepts 3, 4 and 7, 8
Beaker A is made of steel and Beaker B is made of
glass. Both set-ups are placed in the open field with
direct sunlight for 20 minutes. David then measures
the amount of water. The amount of water in Beaker
A drops to 280ml and the amount of water in Beaker
B drops to 290ml. Explain David’s results.
300ml of
Water
Beaker A
Beaker B
Scientific thinking process:
The question is showing different materials.
This means question wants you to apply the science
concepts of 3 and 4: Good and poor conductors of heat.
Also, question also mentions amount of water
decreases. This means there is evaporation of water.
Apply Science concept 8: Higher temperature will cause
water to evaporate faster.
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Answer:
Beaker A is made of steel which is a better conductor
of heat than glass. The water in beaker A gains heat
from the steel at a faster rate.
Result:
Temperature of water in beaker A will rise faster than
the water in beaker B. Rate of evaporation is faster in
beaker A than in beaker B
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Describing the process of evaporation of water
9) Gains heat and evaporates into water vapour
Example: Water gains heat from the (heat source)
and evaporates into water vapour.
Describing the process of condensation of water
vapour.
10) Water vapour rises, touches the cooler surface of the
container, loses heat and condenses to form water
droplets.
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Combining Concepts 9 and 10
The setup below is placed in the open field under
direct sunlight for a few hours. Explain why water
droplets are formed in the glass container after a few
hours?
Sun
Glass
container
Water
droplets
300ml of
water in
beaker
Scientific thinking process:
Look at the clues in the diagram.
-
Liquid water in a beaker
Water droplets form on the inner surface of the
glass container
Question wants you to apply concepts 9 and 10:
Evaporation and condensation of water.
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Answer:
Water in the beaker gains heat from the sun and
evaporates into water vapour.
Warm water vapour rises, touches the cooler inner
surface of the glass container, loses heat and
condenses to form water droplets.
Note:
-
Please write “warm” in this type of question.
-
Please remember to write “the sun” in this
question.
(If the water is hot in the first place, you don’t have
to mention heat source)
-
You have to mention “inner surface”.
-
To communicate clearly, use the labels in the
diagram. Don’t use your own words.
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Must Know Three states of matter Concept
11) The object has fixed shape and fixed volume.
Example: Glass has a fixed shape and volume
Recommended not to write: “Definite” to reduce
spelling error.
12) The object has no fixed shape but it has a fixed
volume.
Example: Water has no fixed shape and but has a fixed
volume
13) The object has no fixed shape and no fixed volume.
Example: Air has no fixed shape and volume.
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Combining Concepts 11, 12 and 13
Example
Study the sealed container as shown below. The
sealed container has a total volume of 1000cm3.
500cm3 of rocks is added and 100cm3 of air is pumped
into the container.
Sealed
container
200cm3 of
water in
sealed
container
What is the final volume of air inside the sealed
container? Explain your answer.
Answer:
1000 - 500 (rocks) - 200 (water) = 300cm3.
Air has no fixed volume and will occupy the remaining
space inside the container.
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Explain process relating to occupying space
14) Substance A flows into the container to occupy the
space when substance B flows out/escapes.
Example: Air flows into the container to occupy the
space when water flows out/escapes from the
container.
Describing balloons taking in/removing air
15) The balloon is inflated.
Meaning: the balloon is filled with air.
16) The balloon is deflated.
Meaning: the balloon has lost all its air.
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Must Know Reproduction in plants Concept
Animal pollination
17) Pollen grains land on the sticky stigma. Pollination
occurs.
Fertilisation of flower
18) Removed stigma, style, ovary, ovule (remove any one
of them) and fertilisation will not take place.
Explain the importance of dispersion
19) To prevent overcrowding and competition for
resources such as sunlight, minerals and water.
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Identify concept 17
Study flower A
Sticky
stigma
Large
colourful
petals
Anther
Based on the information above, which method of pollination for
flower A?
Scientific thinking process:
Look at the clues in the diagram.
-
Bright and colourful petal
Sticky stigma found inside the flower.
These are enough clues to help you determine the flower
is animal pollinated.
Answer: Animal pollination
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Must Know Light and shadows Concept
Explaining how shadows are formed
20) Shadows are formed when light rays are blocked by
opaque objects.
OR
Light rays cannot pass through the opaque object.
Explaining how we see objects.
21) Light is reflected from the object into our eyes.
Example: We see a water bottle because light is
reflected from the water bottle into our eyes.
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Must Know Digestion Concepts
Describe the digestion process
22) The saliva breaks down food into simpler substances.
23) The teeth cuts/chews the food into smaller pieces.
Take Note: You have to know the difference between
smaller pieces and simpler substances.
Glucose and digested food are simple substances.
Starch and undigested food are complex substances.
Explain how churning food speeds up digestion.
24) Stomach walls churn the food so the digestive juices
will mix with the food and breaks down the soft food
into smaller pieces.
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Must Know Circulatory System Concepts
Describe how are substances transported.
25) Blood transports oxygen, digested food and water to
the body cells.
26) Blood transports waste substances and carbon
dioxide to the organs for removal from the body.
Take note: Blood does not remove substances.
Take note: Blood is found inside the blood vessels
Describe what happens to food substances after
reaching the body cells
27) Body cells take in digested food and oxygen during
respiration to release energy for life processes.
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Must Know Food Chains and Food Web Concepts
Understanding population
28) Different/types of population species
Example: There are three different population of
insects living in the garden community.
Note: This means 3 different species of insects.
29) Total Population.
Example: Total population of butterflies in a garden
community is 25.
Note: This means there are 25 organisms of butterflies
in a garden community.
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Must Know Electricity Concepts
Explain why other bulbs will not light up when a bulb
is fused in a series circuit
30) In series circuit, there is one path for electricity to
flow.
Example: When a bulb fused in a series circuit, the
other bulbs will not light up as there is no other path
for electricity to flow.
OR
Example: The bulbs are arranged in a series circuit.
When one bulb is fused, it becomes an open circuit
and no electricity can flow.
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Explain why other bulbs will light up when a bulb is
fused.
31) In parallel circuit, there are a few/more than one
paths for electricity to flow in a circuit.
Example: When one bulb is fused in a parallel circuit,
the other bulbs remain lit as there are other paths for
electricity to flow.
Connection of bulbs to the wires.
32) One end of the wire is connected to the metal casing
and the other end of the wire is connected to the
metal tip. The bulb will light up.
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Identify the correct concepts
Switch
Bulb A
battery
Bulb B
The bulbs, switch, wires and battery are working
properly.
Which bulb, A or B, is lit when the switch is closed?
Answer: bulb B.
Scientific thinking process:
Both ends of the wire are connected to the metal casing in bulb
A.
Take note: one end of the wire must be connected to the metal
casing, the other end to the metal tip.
Concept 32 is used.
Bulb A does not light up.
Metal casing is an electrical conductor. Electricity can flow
through the metal casing into bulb B.
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Must Know Brightness of Bulbs Concept
33) Bulb added in series.
Example: As more bulbs are added in series, all the
bulbs are dimmer.
34) Bulbs added in parallel.
Example: As more bulbs are added in parallel, there is
no change in brightness.
35) Batteries added in series.
Example: As more batteries are added in series, the
bulbs shine brighter.
36) Batteries added in parallel.
Example: As more batteries are added in parallel,
there is no change in brightness of the bulbs.
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Explain why one bulb is brighter than the other.
37) There are more batteries supplying electricity to Bulb
A than Bulb B. Hence bulb A is brighter as there is
more electricity flowing through Bulb A.
OR
There is more electricity flowing through Bulb A than
Bulb B. Hence Bulb A shines brighter than Bulb B.
Explain why one bulb is dimmer than the other.
38) There are less batteries supplying electricity to Bulb B
than Bulb A. Hence bulb B is dimmer as there is less
electricity flowing through Bulb B.
OR
There is lesser electricity flowing through Bulb B than
Bulb A. Hence Bulb B shines dimmer than Bulb A.
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Iron core
Must Know Electromagnetic Concepts
Describe how
electromagnet.
the
iron
core
becomes
an
39) In a closed circuit, electricity flows through the coils
of wire around the iron core, the iron core is
magnetised and becomes an electromagnet.
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Applying concept 39
Closed switch
Iron core
Steel nails
Explain how does adding more batteries in series
attract more steel nails?
Answer: When more batteries are added in series,
more electricity flows through the coils of wire around
the iron core, the iron core is magnetised and
becomes a stronger electromagnet.
Describe the process of electromagnet losing its
magnetism
40) In an open circuit, no electricity flows through the
coils of wire around the iron core, the electromagnet
loses its magnetism and no longer attracts the
magnetic material.
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Must Know Forces Concepts
41) The compressed spring exerts an elastic spring force
on the object.
Do not write: the object has elastic spring force.
42) The magnet will attract the magnetic material.
Don’t write: the magnet will pull the magnetic
material.
43) There is frictional force between the object and
another object.
Example: There is frictional force between the
wooden block and the sandpaper. Hence the wooden
block stops moving down the slope eventually.
Note: Since frictional force is a contact force. It is good
to mention the two objects/surfaces involved.
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Must Know Energy Concepts
Explain conversion of energy.
44) Type of energy from Object is converted to type of
energy.
Example: chemical potential energy from the battery
is converted to electrical energy.
45) Useful energy
Example
State the useful energy conversion of the Computer
when Tom is watching a video.
Electrical energy is converted to light and sound
energy.
Don’t write: Heat energy. This is not a useful form of
energy.
Take Note: Watching video has both Light and Sound
energy.
- 30 -
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About the Author
Hi there,
Glad to meet you.
My name is Andy Ling and I
have been teaching science over
the past 5 years (from upper
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To All Concern Parents
Does your child have problems understanding certain
concepts?
Does your child frequently write out of point in open ended
questions?
Does your child always lose marks when they thought their
concept is right?
Does your child always have the habit of writing only one
sentence in “explain why” questions?
If your answer is “yes” to the above, your child needs help
NOW!
We are a team of science experts that help your child to
master the open-ended questions with great confidence.
We don’t just teach concepts, we teach them real life
application questions that are fun and engaging to the
students.
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