CAMBRIDGE PRIMARY SCIENCE 4 TEACHER’S RESOURCE

Workbook answers
Unit 1 Living Things
1.1 Bones and skeletons Challenge
Focus 3 Animal Skeleton
1 skull Bird C
Rabbit D
jaw Frog B
rib cage Crocodile A

arm bones 4 W is the skull

X is the ribcage
spine
Y is the spine
Z is the hip

1.2 Why we need a skeleton

Focus
1 Skull – Protection; Ribs – Protection;
Arm Bone – Movement; Spine – Support and
Protection (the spine protects the spinal cord).
leg bones Practice
2 a A skeleton is important because it makes
a frame that supports the body; it allows
us to move; it protects organs inside the
body and holds them in place.
b The baby would stay small and not grow
into a child.
Practice
c A broken bone
2 a Skull
d They can take an X-ray picture.
b Rib cage
e The ends of the bone grow back together.
c Spine
f The skeleton can grow big to support a
d Jaw bone
large animal. A worm cannot grow very
e Different bones have different jobs, so big because it does not have a skeleton to
they need to be different sizes and shapes support it.
(or similar answer).

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Challenge b Part C lifts

3 a Meshack
b 14 cm
c Ali is the oldest. His upper arm bone
is longer than Ahmed’s. Our bones get
longer as we get older.
d Ali, Nasreen, Ahmed. Ali has the longest
upper arm bone, Ahmed has the shortest.
e Fatima and Meshack
f They have the longest upper arm bones.
g That skeletons grow and allow us to grow.
h Learners should add a bar that is shorter/ c Part B relaxes/contracts and gets shorter/
lower than the bar for Ahmed’s arm bone longer. Part B pulls/pushes on part C and
length, e.g. 8 cm. makes it drop/lift.

1.3 Skeletons and movement 1.4 Different kinds of skeletons

Focus Focus
1 When I lift a weight, the muscle at the front of 1 Tick boxes below fish, cat and rabbit.
my arm contracts and gets shorter. The muscle 2 a Vertebrates
at the back of my arm relaxes and gets longer.
This shows that muscles work in pairs. b Invertebrates
2 Add labels to drawing: top label – the muscle c Exoskeleton
relaxes; lower label – the muscle contracts. d Cross in box below beetle and snail
Practice Practice
3 Muscles work by pulling on the bones they are 3 a a is a bee
joined to. Muscles work in pairs. When one
muscle contracts/relaxes, the other b is an ant
muscle relaxes/contracts. The muscle that c is a spider
contracts gets shorter. The muscle that relaxes
d is a centipede
gets longer.
e is a snail
4 The muscle that is working contracts/relaxes.
The muscle that is resting contracts/relaxes. f is a worm

Challenge g is a slug

5 a A upper arm bone; B biceps muscle; b They do not have a backbone.

C lower arm bone; D triceps muscle. c Bird or bat
Fish, seal, dolphin, whale, or snake

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Challenge
4 Row two left-to-right: Does it have fur? Does it
Unit 2 Energy
have legs? 2.1 Energy around us
Row three left-to-right: Does it have a short
tail? Does it have feathers? Does it have four
Focus
legs? Does it have fins? 1 a Movement
b Movement
1.5 Medicines and infectious
diseases c Heat and light
d Sound and movement
Focus
1 A 
Medicines make us better when we
Practice
are sick. ✓ 2
Sentence True False
B Check with an adult before you take any a Things that do not move
medicines. ✓ ✘
do not have energy.
C Medicines cannot stop us from getting b Our bodies contain
illnesses. ✘ ✓
energy.
D Plants and animals can have infectious c There is light energy in
✘
diseases. ✓ wind.
Practice d A stove gives off heat
✓
energy.
2 a i n j e c t i o n e A television set gives off
movement energy and ✘
n w e r t a n i o sound energy.
h a s d f b h n l f There is energy in running
✓
water.
a c b r u l l t h
l e d i n e m m d 3 a Energy makes the stroller move.
b Energy makes wet washing dry.
e v f p q t d e f
c Energy changes the raw egg into a cooked
r u r k l g o n u egg.
m i x t u r e t p d Energy makes the rattle make a sound.

b Injection; some learners may also say Challenge

tablets as we take tablets to prevent 4
diseases like malaria. Mixed-up Form of Something
word energy that has this
c Inhaler form of energy
Challenge ghitl light Sun/lamp/bulb/
3 Marcus took medicine meant for someone candle/torch
else. He did not check to see whether he veomtnem movement ball rolling/
should take it or how much he should take. person/cycling/
running water
He did not check that the tablets were meant
for headaches. ehte heat stove/fire/Sun/
heater/toaster
He did not ask an adult to help him take
the medicine. nosdu sound radio/TV/
phone/musical
instrument

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5 a The ball had energy. a Heat moves from the hot water to the
spoon. The heat moves from the spoons
b The ball did not have enough energy to
to the petroleum jelly and melts it, which
move that far.
makes the bead fall off.
c Sofia can throw the ball harder. This will
b 40 °C
give it more energy and it will move a bigger
distance. c 100 °C

2.2 Energy transfers d The bead falls off faster when the
temperature is higher.
Focus e The hotter the water, the more energy it
1 a Food → donkey has that can be transferred/move to the
spoon.
b Air → balloons
f Any from 13 to 15 minutes is acceptable.
c Fire → meat
Data point and line segment added to
d TV set → person graph.
Practice 2.3 Energy changes
2 The heat energy from your hand is transferred
to, or moves to, the ice which makes the ice
Focus
melt. 1 a 
Electrical energy →
3 a Movement energy light energy + heat energy

b There is a transfer of movement energy b Electrical energy → heat energy + sound

from your hand to the toy to make the energy
toy move. c Movement energy →
4 Sun → solar panels → water heat energy + sound energy
d Movement energy → sound energy
Challenge
5 16
Practice
15 2
14 Picture What form Where Does the
13 of energy is does the form of
Time for bead to fall off in minutes

12 transferred? energy go energy

11 to? change?
If so, how?
10
A heat the food/ no change
9
water in the
8
pot
7
B movement the block of sound
6 wood, sur-
5 rounding
4 air
3 C electricity heater heat,
2 movement
1 D movement trampoline heat
0 E light plant food
10 20 30 40 50 60 70 80 90 100
Water temperature in °C

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Challenge e Yes. The herbivore will always eat the

producer/plant, and the carnivore will
3 a To make them warm always eat the herbivore.
b Movement energy → heat energy 4 a 
An animal that eats plants and other
c Electrical energy is changed in the light animals.
bulb into light energy. b Grass → deer → bear → tiger
d Electrical energy → light energy + heat
energy + sound energy
e The banana Unit 3 Materials
f Energy in food → movement energy in legs 3.1 Materials, substances and
g Sound energy particles
h The sound energy moves/is transferred
Focus
from the bell through the air to Vikal’s
ears. 1 a Liquid
b Solid
2.4 Energy and living things
c Solid
Focus
d Liquid
1 a Cabbage → snail → duck
e Liquid
b Leaf → caterpillar → bird
f Solid
c Corn → locust → lizard → cat
Practice
d Melon → mouse → snake → eagle
2 a b
Practice
2 a The plant
b Herbivores
c Rat, rabbit
d Eagle, rat
e Rat and rabbit are prey for eagle; rabbit is Solid Liquid
prey for rat.
a All substances are made of particles.
f Rat – it eats plants and animals
b Solids have a fixed shape due to their tightly
g Plant → rat; or plant → rabbit packed particles which move in a fixed
h Plant → rat → eagle; plant → rabbit position.
→ eagle or plant → rabbit → rat c Liquids can spread and take on the shape
Challenge of their container.
3 a T
 he grass plant produces food for the Challenge
deer/herbivore. 3 a Drawing A – liquid; drawing B – solid
b The grass uses energy from the Sun to b The particles in liquids (A) are not as
makes its own food. close together as the particles in solids.
c The direction in which the energy in the They have larger spaces between them and
food is passed along the food chain. can move more freely than in solids.
d The energy in the grass passes to the deer c  he particles in solids (B) are held tightly
T
when it eats the grass. The energy in the together. They have small spaces between
deer passes to the tiger when it eats the them and cannot move freely.
deer.

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4 a 
Solids have a fixed shape because their Challenge
particles do not move very much.
6 a
b Liquids can change shape in some ways 10
because their particles can move around

Time taken for sand to flow in minutes

each other.
8
3.2 How do solids and liquids
behave?
6
Focus
1 a
4

0
0 50 100 150 200 250 300 350 400 450 500
b To make it a fair test. Volume of sand in ml

2 Particles in a liquid are close together, but they b The time taken for the sand to flow
can slide past each other and change places. increases as the volume of sand increases.
Because of this, a liquid can change shape
c  he size of the sand grains, the size of the
T
easily.
hole in the funnel, how dry the sand is, or any
3 a No other suitable idea.
b Particles in a solid are packed close d Bigger grains flow faster; the bigger the
together in fixed positions. They cannot hole in the funnel, the quicker the sand
change shape easily. flows through it; dry sand will flow faster
than wet sand because there is more
Practice airspace in the dry sand.
4 In solids, the particles are packed close
together in a fixed position. They cannot move 3.3 Melting and solidifying
freely. This explains why solids have a fixed
shape. Focus
In liquids, the particles are closely packed 1 a Liquid
but further apart than in solids. This allows b Solid
the particles to move past one another. This
c You must cool it.
explains why liquids, such as water, can flow cool
and take the shape of the container they are d Water (liquid state) ice
in. (solid state)
5 a Sand can flow or be poured. 2 a Solid
b Sand is made up of lots of tiny grains. b Liquid
There is air between the grains which c Melting
means that the grains have space to move heat
into. This lets the grains flow past one d Butter (solid state) butter
another like the particles in a liquid. (liquid state)
c Any two, such as flour, salt, sugar or
uncooked rice.

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Practice Practice
3 a B 2 a True
b C b False
c A c True
d A d True
e D e False
Challenge f False
4 a 80 °C 3 a Yes
b 10 °C b A new substance formed.
c 14 minutes Challenge
d He should put the same amount of water 4 a A Water B Air
in each beaker; ice cubes must be the same
size. b There was water and air in tube A.

e Ice melts faster in hot water than in cold There was no water in tube C.
water (or similar conclusion). There was no air in tube D.
f When we heat the ice, the heat energy To rust, the iron must be in contact with
makes the particles move faster and move water and air.
away from each other. This makes the
c Steel does not rust like iron.
solid ice melt and become liquid water.
When we increase the water temperature Do all metals rust in the same way? (Or
we add more heat energy. This makes the similar question.)
particles move even faster so they move Do all metals rust? (or similar question)
away from each other quicker, which
makes the ice melt faster. d Factors can include the shape and size of
the test tubes and the amount of water in
g It would take less time for the crushed ice each test tube.
to melt. The heat energy in the water only
e The type of metal the nails or other
has to be transferred to small pieces of
objects are made from.
ice. This transfer will happen quicker than
a heat transfer to bigger ice cubes.
h He can ask an adult to heat the water Unit 4 Earth and its
for him. He should wear protective
gloves and clothing when he works
with the hot water.
habitats
4.1 The structure of the Earth
3.4 Chemical reactions
Focus
Focus
1 The internal structure of the Earth describes
1 a Chemical reaction what is below the surface.
b No chemical reaction The Earth’s crust is thinner below the oceans
c Chemical reaction than below the land.

d Chemical reaction The outer core of the Earth is liquid.

e No chemical reaction The core consists of metals.

The mantle consists of magma.
The Earth’s crust is the thinnest layer of
the Earth.
The temperature increases as you get closer
to the centre of the Earth.

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The core is the thickest layer of the Earth. Practice

The inner core of the Earth is solid. 2 a The world map in the Workbook is
Magma is a liquid material. centred on Africa and Europe. So, the
Pacific Ocean is half on the left-hand side
Practice and half on the right-hand side.
2 a Label from top to bottom:
Crust
Atlantic Ocean
Mantle
Outer core
Inner core
b Crust – rocks
Mantle – magma b It is called the Pacific Ring of Fire
because there are many active volcanoes
Outer core – metals
along it.
Inner core – metals
c Parts of the world where there are lots of
c Crust – solid breaks in the Earth’s crust have lots of
Mantle – liquid volcanoes. Parts of the world where there
no breaks in the Earth’s crust have no
Outer core – liquid volcanoes.
Inner core – solid
Challenge
Challenge 3 A-6; B-1; C-4; D-3; E-2; F-5.
3 a 12 km
b It is too hot.
4.3 Earthquakes
c The speed of earthquake waves passing Focus
through the Earth. 1 a An earthquake happens when there is a
sudden movement of rocks in the Earth’s
4.2 Volcanoes crust. This creates huge amounts of
energy. The energy transfers into waves.
Focus
The waves travel through the Earth’s crust
1 When a volcano erupts, magma from the to the surface.
mantle reaches the surface through a crack in
b Any three from:
the crust. When magma reaches the surface it
is called lava. • buildings collapse
Sometimes lava and ash come out of the • landslides and mudslides
volcano. These materials build up to form • flooding
a cone shaped mountain called a composite
volcano. • railway lines bent
When the lava is very hot it runs quickly • bridges and roads destroyed
over the surface. The islands of Hawaii were • electricity lines broken
formed like this. The lava cools to form black
rocks. • fires caused by broken gas pipes.
c The Pacific Ring of Fire

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Practice c A giraffe has a long, thick tongue to curl

round branches and bring the leaves to his
2 a A tsunami mouth.
b When an earthquake begins under the Its mouth is covered with very thick skin
sea a huge wave develops. When the huge to protect it from the thorns.
wave reaches a low-lying coastal area it
floods the land.
c The village will be flooded and there will
be a lot of damage. The people could be
Unit 5 Light
seriously injured or drown. 5.1 How we see things
Challenge Focus
3 a Buildings must be built with deeper, 1 a The Sun
stronger foundations to reduce the effects
of shaking. b Light travels from the Sun to the palm
tree. The light reflects off the palm tree
b They notice animals behaving strangely. into Arun’s eyes. This is how Arun sees the
For example, snakes come out of their palm tree.
winter sleep.
Practice
4.4 Animals in different habitats 2 a A lamp
Focus b The needle and the thread
1 a 
Very cold with snow and ice (North Pole/ c Light travels from the Sun to her sewing.
Arctic) The light reflects off her sewing into Mrs
b Polar bear Liong’s eyes. This is how she sees her
sewing.
c Polar bears have very thick fur to help
keep them warm. Challenge
Polar bears have a thick layer of fat to 3 a A box of books.
help keep them warm. b It is too dark.
2 a Water c She must shine a flashlight into the
b A fish cupboard.
c A fish has gills to allow it to take in oxygen d The light from the flashlight travels to the
under water. Its fins and shape allow it to box of books. The light reflects off the
swim well. box of books into Zara’s eyes. This is how
she sees the box.
Practice
3 a Bird C (and B) 5.2 Light travels in straight lines
b Bird D Focus
c Bird A 1 Sofia shines the flashlight down the tube. Zara
d A duck, swan, goose or other water bird can see the light when she looks up the tube
from the other end.
e Bird B
Sofia makes a bend in the tube. She shines the
f An eagle, falcon, owl, hawk or other bird flashlight again down the tube. This time Zara
of prey cannot see the light.
Challenge This demonstrates that light travels in
4 a Tropical grasslands with thorn trees. It is straight lines.
hot and dry most of the time.
b By using/extending its long neck.

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2 a The Sun 5.3 Light reflects off different

b surfaces
arriving
ray Focus
refle 1 a Smooth and shiny surface
cted
ray
b Image or mirror image
c Light shines from the lamp on to Zara’s
face. Light from Zara’s face travels to the
mirror. The mirror reflects Zara ‘s image
Practice into her eyes.
3 a The lamps. d Wood absorbs/does not reflect light.
b Light shines on Khalid. Light reflects off Practice
Khalid and travels into Rabah’s eyes.
2 a Aluminium foil
c Rabah cannot see Khaild when he goes
around the corner because light cannot b Reflects light
travel round corners. Light travels in c Water
straight lines.
d All surfaces reflect some light, otherwise
4 we could not see them.
arri
vin reflected ray
Challenge
g ra
y
3
Order of Event
event
The light reflects off the cars
2
behind Mr Damsong.
Mr Damsong sees the cars
6
behind him.
Challenge
The light reflects off the rear
5 4
view mirror.
The light travels into
5
Mr Damsong’s eyes.
The light travels to the rear
3
view mirror.
Light from the Sun shines on
1
the cars behind Mr Damsong.

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5.4 Light in the solar system g The rocks contain iron oxide.
The atmosphere consists mostly of
Focus carbon dioxide.
1 a Letter on 5.5 Day and night
diagram
Moon D
Focus
Sun C 1 a
Earth E
Orbit of the Moon around B Sun’s rays
the Earth
Orbit of the Earth around A
the Sun Spin
A planet E
A star C
A body in space that C Earth’s axis
gives out light
b 24 hours
A body in space that E or D
reflects light c Learners should colour in the part facing
away from the Sun on the diagram. This
b Mercury, Venus, Earth, Mars, Jupiter, is the half of the Earth to the right of the
Saturn, Uranus, Neptune vertical line.
c Asteroids, moons and comets Practice
Practice 2 a The Earth spins on its axis and makes one
2 a The solar system complete turn in 24 hours. Almost every
place on the Earth faces the Sun and has
b The Sun day for part of the 24 hours. When a place
c 2 – Mercury; 3 – Mars; 4 – Neptune is facing away from the Sun it has night.

d 365¼ days or 1 year b All the planets orbit the Sun. When parts
of each planet face the Sun, these parts
e A shorter time have day, and parts facing away from the
f Venus is closer than the Earth is to Sun have night.
the Sun. c Longer
g Neptune d Shorter
Neptune is the planet furthest from Challenge
the Sun.
3 a Day
Challenge
b Venus
3 a A planet
c 121½ Earth days
b Further from the Sun
d Jupiter
c A telescope magnifies everything (makes
e 2½ hours (6 hours on Earth is one quarter
everything look bigger).
of 24 hours. So on Jupiter one quarter of
d They looked at the night sky with their 10 hours is 2½ hours)
eyes.
e They knew it was red in colour.
5.6 Investigating shadow lengths
f They discovered that Mars has Focus
two moons. 1 a 12:00
They discovered that there was ice on Mars. b Short

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c 09:00 and 15:00

d Long 2 Object Material Electrical Electrical
object conductor insulator
e During the morning the shadow becomes
is made
shorter and is shortest at midday. During
from
the afternoon the shadow becomes longer.
1 Key metal ✓
f The shadow at 18.00 will be beyond the
shadow at 15:00 and much longer. 2 Bottle glass ✓
3 Toy duck plastic ✓
Practice
4 Paper clip metal ✓
2 S
S S 5 Book paper ✓
S S 6 Shopping plastic
✓
Bag

Practice
3 a Circuit A – Yes; circuits B, C and D – No
b Material A is an electrical conductor
and materials B, C and D are electrical
insulators.
c Materials made of metal, such as the key,
12:00 are electrical conductors. Materials made
09:00 11:00 13:00 15:00
of ceramic, plastic and cork are insulators
of electricity.
a The Sun appears to move across the sky.
b No. The Sun only appears to be moving. Challenge
It is actually the Earth that is moving as it 4 a Holding the plastic covered wires, allow
spins on its axis. the bare metal wires to touch each other.
If the lamp lights up, the circuit works.
Challenge
b Coin ✓ chopstick ✘ glass ✘ plastic
3 a 10:00 – drawing 5
spoon ✘
12:00 – drawing 2
c Test each object by holding one of the
16:00 – drawing 4 plastic-coated wires in each hand so that
19:00 – drawing 3 the bare wires touch two different parts of
the object. Observe the lamp. If the lamp
b The position of the Sun and the length of lights up, the object conducts electricity.
the shadow. If the lamp does not light up, the object
does not conduct electricity.
Unit 6 Electricity d Metals are conductors and non-metals are
insulators of electricity.
6.1 Which materials conduct Object Material Electrical Electrical
electricity? object conductor insulator
is made
Focus from
1 a A material that allows electricity to pass Key Metal ✓
through it is an electrical conductor.
Glass Glass ✓
b A material that does not allow electricity bottle
to pass through it is an electrical insulator.
Spoon Plastic ✓
Cork Cork ✓

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6.2 Does water conduct Practice

electricity? 2 a An electric kettle.
Focus b The plastic insulation on the electric wire
has worn away. This exposes the metal
1 a Pure water is water with no salts dissolved
wire. The metal wire conducts electricity.
in it.
If a person touches the wire they will get an
b Tap water contains salts dissolved in it. electric shock.
c They can conduct electricity because they The kettle is close to the sink. The water has
contain water with salts dissolved in it. salts dissolved in it. Salty water conducts
electricity. So a person who touches the bare
Practice
wire with wet hands will get an electric shock.
2 Assess poster using this grid:
Challenge
Does Yes, very Yes, fairly No
3
poster… well well
catch peoples’
attention? Pylon

contain a
picture that
clearly conveys
the message? Ceramic separator
contain a short
clear written
warning?
Cable

Challenge
a The cables are made of metal because
3 a Jawad got an electric shock metal is a good conductor of electricity.
b A The electricity was switched ON. b Copper
B The plastic insulation had worn off c The separators are made of ceramic because
the wire where he held it. ceramic is a good insulator of electricity.
C He had sweaty hands. Salt water 4 Arun and Marcus must not climb the pylon.
conducts electricity. They could fall, and if they touch the cables they
will get an electric shock which will kill them.
6.3 Using conductors and
insulators in electrical appliances 6.4 Switches
Focus Focus
1 a A is an electric kettle; B is an electric 1 a A switch open or closes a circuit.
hairdryer and C is an electric mixer/whisk. b The lamp should light up in circuit B.
b 110 V or 220 V (or similar, depending on In circuit B the switch is closed so the
location). electricity can pass through the circuit.

c Plastic c A switch causes a break in a circuit when

it is open, as in circuit A. The electricity
d An electrical insulator. cannot flow all around the circuit.
e Electrical insulators do not conduct
electricity.
f The wires are the electrical conductors.
These are inside the appliances.

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Practice Practice
2 a No, electricity is not flowing in circuit A. 2 a Three cells, a cell holder, three lamps,
b The switch is open. three lamp holders, a switch and five
connecting wires.
c Close the switch.
b No. The switch is open.
d Yes, electricity is flowing in circuit B.
c More brightly
e The switch at the wall is turned on. (Not
‘heat is coming from the iron’.) d Less brightly

f Turn off the switch at the wall. e Less brightly

f More brightly
Challenge
3 a A cell, a switch, a lamp, a lamp holder
Challenge
and connecting wire. 3 a Learners should circle everything except
b The switch is closed. one of the lamps in a lamp holder and
one of the cells.
4 a The switch is open so the circuit is broken.
b You can stick two cells together using the
b They must close the switch so that the sticks and tape. Make sure that the + end
circuit is complete. of each cell is next to the – end of the cell
next to it.
6.5 Changing the number of
c The lamps will come on if I close the
components in a circuit switch, but not if I leave the switch open.
Focus d The remaining lamp will burn more
brightly.
1 a Cells, lamps, lamp holders, connecting
wire and a switch. e The same strength of electricity will only
be used by one lamp instead of two lamps.
b Close the switch.
f The lamps will burn less brightly.
c Less brightly
g The same strength of electricity will be
d The same strength of electricity has to be
shared between three lamps instead of
divided between three lamps instead of
two lamps.
two lamps.

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