CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
Workbook answers
Unit 1 The human body
d
Yes. The measurement for digging. The
pulse rate measured is low although he is
doing a physical activity. We would expect
the measurement to be higher.
He should do all the activities for the
same length of time, then measure his
pulse rate. He should also start each
activity after a period of rest (sitting still)
to allow his heartbeat to return to normal.
Topic 1.1: The circulatory system
Focus
1
Heart, blood and blood vessels (in any order)
2
a
The heart pumps blood through the body.
b
The left side of the heart pumps blood
that contains oxygen.
c
The right side of the heart pumps blood
without oxygen to the lungs.
d
Blood is carried in the blood vessels.
e
Blood carries food and oxygen to all
parts of the body and takes away waste
products.
a
d
b
e
B
B
C
C
c
A
a
160
1
Bar chart of pulse rates
after different activities
Heartbeats per minute
140
120
100
2
60
40
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1
Marcus’s pulse rate would increase. The
more active you are, i.e. pedalling faster,
the more often your heart must beat to
carry enough food and oxygen from the
blood to your muscles.
We breathe in air through our nose or mouth.
The air we breathe in contains oxygen gas.
The air moves down the windpipe and into
our lungs. The oxygen in the air then moves
from the lungs into the blood. We breathe out
air that contains carbon dioxide gas. The ribs
protect our respiratory system.
air enters
the nose
air moves
down windpipe
into lungs
20
lungs fill
with air
sit
c
g
Practice
80
0
b
Body activity/exercise makes the pulse
rate increase.
Focus
Challenge
4
f
Topic 1.2: The respiratory system
Practice
3
e
Marcus’s pulse rate was lowest when he
was sitting still. The body needs less food
and oxygen when it is still or inactive, so
the heart does not have to beat fast.
diaphragm
moves
downwards
3
Nose and mouth → windpipe → lungs → blood
Playing football
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
that menstruation usually begins about a
year after the start of puberty.
Challenge
a
Graph of pulse and breathing rate after exercise
140
b
i
12 years
ii
120
c
i
11 ii
7
d
i
Puberty starts when girls have an
average mass of 45 to 47 kg.
ii
Body mass
iii
Better nutrition/more food makes girls
grow faster, so their mass increases and
they reach puberty earlier.
100
80
60
40
20
0
10
0
20
30
40
50
60
Breaths per minute
b
c
As the pulse rate increase, the breathing rate
also increases during exercise OR The higher
the pulse rate, the higher the breathing rate.
i
ii
The person with a pulse rate of 100
heartbeats per minute and a breathing
rate of 26 breaths per minute.
Learners’ own suggestions, for
example, the breathing rate was not
accurately measured, or the person
had a very large lung capacity.
d
Accept answers of between 116 and 124
heartbeats per minute.
e
After jogging on the spot for three
minutes, a person with a high breathing
rate has a higher pulse rate than a person
with a low breathing rate.
Topic 1.3: The reproductive
system
Focus
1
Reproduction – making more individuals of
the same kind of living thing
Puberty – the age at which a person becomes
able to reproduce
Ovum – female sex cell
Fertilisation – joining of a male sex cell and
female sex cell
Uterus – the baby develops here
Testis – male sex cells are made here
Sperm – male sex cell
Ovary – female sex cells are made here
Practice
2
a
d
C;
A;
B;
C
c
B;
Challenge
3
2
a
Focus
1
a
d
Any three from: grows taller; skin becomes
oily, more body hair grows, breasts develop;
hips get wider; voice gets a little deeper. Note
b
e
False
True
c
f
True
True
False
False
Practice
2
Learners’ drawings should indicate tears,
mucus, skin and acid in the stomach. See
drawing in Learner’s Book section titled ‘The
body’s defences against diseases’.
Challenge
3
a
By a parasite
b
Mosquitoes spread the malaria parasite but
do not cause the disease or get it themselves.
c
i
Graph of reported malaria cases
1000
800
600
400
200
0
Jan–Mar
Apr–Jun
Jul–Sep
Oct–Dec
Months of the year
d
b
e
35
Topic 1.4: Diseases
Number of malaria cases
Heartbeats per minute
4
ii
January to March
iii
July to September
iv
The fewest cases occurred in the dry
season and the most cases in the wet
season. Mosquitoes breed in the wet
season (or similar answer).
Any three from:
• sleep under bed nets
• wear long sleeves and long pants
• keep doors and windows closed at
night when mosquitoes are active
• use insect repellents on their skin to
keep insects away
• burn mosquito coils to keep insects away
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
2 Materials: properties
and changes
Topic 2.1: Materials: properties
and changes
e
Challenge
5
Focus
1
Boiling point is a property of a substance, so
different substances will have different boiling
points.
2
a
Cooking oil
b
Nail polish remover
c
About 130 °C
d
Evaporation
3
Boiling point is a property of a substance,
and we know that water boils at around
100°C, or similar answer.
a
Olive oil, vinegar, water
b
Water
c
Check bar graph using this checklist:
Did the learner:
Yes
choose a suitable scale for
the vertical axis so that the
boiling point of olive oil will
fit easily?
use a ruler to draw the axes?
label the vertical axis
Boiling point in °C and the
horizontal axis Liquids?
draw the bars accurately to
fit the scale?
label each bar?
give the bar graph a title?
Temperatures marked off at 50.5 °C, 60 °C,
100 °C.
Boiling point of water: 100°C
100
90
80
70
60
Melting point of candle wax: 60°C
50
Boiling point of acetone: 50.5°C
40
30
d
Bar with height at 184 °C added to graph
e
Cooking oils boil at a much higher
temperature than water. So, a burn from
boiling oil will be much worse and more
dangerous than a burn from boiling water.
20
10
0
Topic 2.2: Thermal and electrical
conductors
Focus
Practice
4
3
1
a
Drawing B
b
Evaporation
c
i
In both processes liquid water
changes into water vapor gas.
ii
Boiling happens when water is heated
to 100 °C; evaporation happens at
much lower temperatures; bubbles
of gas form throughout the liquid
in boiling, no bubbles form in
evaporation.
d
No
i
Beaker A – any temperature in
normal room temperature range of
about 20–30 °C
ii
Beaker B: 100 °C
a
i
All the metal parts: filament,
wires, base
ii
The glass bulb
b
Plastic is not an electrical conductor.
The plastic protects you from getting an
electric shock when you touch the plug.
c
i
Metals are good conductors of heat.
The metal spoon would conduct the
heat from the soup to your hand,
which could burn your hand.
ii
Wood is not a good conductor of
heat, so the wooden spoon would not
get hot and burn your hand.
Practice
2
a
i
Silver, copper, aluminium, brass, iron,
stainless steel
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ii
b
Graph of how well metals conduct heat
450
400
Heat conduction
350
300
250
200
Average brightness of lamp
CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
150
6
5
4
3
2
1
0
0
2
100
b
d
The brightness of the lamp increases as
the length of graphite decreases.
e
Learners should plot a brightness of 6 on
the graph for a 1 cm length of graphite.
f
Graphite is a conductor and a nonconductor of electricity. The answer
depends on the length of graphite used.
Longer lengths will conduct little or no
electricity.
l
um
in
iu
m
Copper is a good heat conductor, so it
transfers heat from the stove quickly to
the food in the pot.
c
Silver is much more expensive than
copper, and copper is almost as good a
heat conductor as sliver.
d
Copper and brass are good heat
conductors, so they the transfer heat
away from the engine quickly to stop
it overheating.
Topic 2.3: Reversible changes
Challenge
Focus
3
1
a
b
4
4
The measurement of brightness for
each length of graphite could be slightly
different for each group. The average
takes into account all the different values
measured (or similar answer).
al
Metals
a
Ice will melt quicker in the metal dish.
Metal is a better conductor of heat than
plastic, so heat energy is transferred more
quickly through the metal to the ice. This
is why we saw the ice on the metal dish
melt more quickly.
2
The plastic dish will feel warmer. When
you touch the metal dish, energy from
your finger is conducted quickly into the
metal. This lowers the temperature of
your hand, so the metal feels cold. Heat
energy from your hand is conducted
slowly into the plastic because it is not a
good thermal conductor, so your hand
does not cool quickly and you do not feel
a lower temperature.
Dependent variable – brightness of lamp
Independent variable – the length of
the graphite
Control variables – the circuit components
14
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sil
ve
r
50
4
6
8
10 12
Length of graphite in cm
a
Reversible
b
Irreversible
c
Reversible
d
Irreversible
e
Irreversible
a
The quantity of solute, one beaker is
heated and the other is not.
b
The quantity of water, the size and shape
of the beaker, and the material that the
beaker is made from.
c
The quantity of solute and whether or not
the solvent and solute is stirred.
d
No. The quantity of solute in the two
beakers is different. In a fair test all
factors must be the same except the factor
being tested.
Practice
3
a
The sugar had not all dissolved.
b
i
She could have stirred the tea more or
heated it up.
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
Stirring moves the particles of solute
(sugar) around in the solvent (tea).
This allows them to spread more
easily into the spaces between the
solvent (tea) particles.
Heating makes the particles of both
solvent and solute move faster. This
allows the solute particles to spread
more easily into the spaces between
the solvent particles until they are
evenly spread.
Topic 2.4: Chemical reactions
iii
See drawing under the heading
‘Dissolving’ in the Learner’s Book.
3
i
The sugar would all dissolve.
ii
The particles of both the solute
(sugar) and solvent (tea) are
constantly moving. This makes them
bump into each other until they are
eventually spread out evenly in the
solution. The solute particles can then
fit into the spaces between the solvent
particles and dissolve. This would
happen slowly because the solution is
not heated or stirred.
ii
c
Focus
1
2
a
i
Time taken for sugar to dissolve
ii
Water temperature
iii
Quantity of sugar, quantity of water
b
A new substance or product forms.
b
Sulfur, iron
c
Iron sulfide
A gas is produced; there is a change of colour;
there is a change in temperature.
Practice
a
d
4
a
b
Graph of time taken for sugar to dissolve
in water at different temperatures
Time to dissolve in seconds
70
60
50
C
i
Carbon dioxide, water
ii
Glucose sugar, oxygen
i
Observe bubbles of gas forming.
ii
Count the number of bubbles formed
over a period of time.
Carbon dioxide comes from the air, water
comes from the soil.
d
Living things need oxygen gas to stay
alive/for respiration; animals cannot make
their own food, so they have to eat plants
or other animals that eat plants in order
to get their energy.
e
i
Photosynthesis
ii
Sunlight, chlorophyll
Topic 3.1 Igneous rocks
40
30
Focus
20
1
10
5
c
3 Rocks, the rock cycle
and soil
80
0
B
A
c
100
90
b
e
B
A
Challenge
Challenge
4
a
20
40
60
Temperature of water in °C
80
c
The time taken for the sugar to dissolve
decreases as the temperature of the water
increases.
d
Increasing the temperature makes solutes
dissolve faster/sugar dissolves faster as the
water temperature increases (or similar
conclusion).
Igneous rocks form when magma or lava
cool down into solid rock. An intrusive
igneous rock forms when magma cools down
inside the Earth’s crust. The magma cools
slowly. This causes the crystals to be large.
An example of one of these types of rock is
granite.
When lava cools down on the surface of the
Earth, an extrusive igneous rock forms. The
lava cools quickly and the crystals are very
small. An example of one of these types of
rock is basalt.
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
All igneous rocks are formed of crystals of
minerals. These give the rock a crystalline
appearance.
e
Over time the top/bottom layers of
sediments become rock.
f
Sediments in sandstone are more finegrained/coarse-grained than in shale.
g
Limestone/Sandstone is formed of
crushed sea shells.
h
Fossils are only found in sandstone/
sedimentary rock.
Practice
2
a
extrusive igneous rock
Practice
2
intrusive igneous rock
b
Intrusive igneous rock – granite
Extrusive igneous rock – basalt
c
Granite has large crystals which you can
see with the naked eye, whereas basalt has
tiny crystals which you cannot see with
the naked eye.
3
Magma cooled down slowly inside the
Earth’s crust to form large crystals. Lava
cooled down quickly on the surface to
form small crystals.
4
d
a
Marcus is correct.
b
The rock is black and shiny but you can’t
see the crystals with the naked eye.
c
The island has a big mountain in the
middle of it. This could be a volcano.
When the volcano erupts, lava covers the
island. The lava cools quickly to form an
extrusive igneous rock such as basalt.
Topic 3.2: Sedimentary rocks
and fossils
Focus
1
6
a
Heat and ice break up rocks in a process
called erosion/weathering.
b
A river erodes/weathers the bottom and
sides of its valley.
c
The river deposits/transports sediments
on the sea bed.
d
Layers of sediments build up on the sea
bed in a process called accumulation/
sedimentation.
It is not crystalline
b
If it is shale, I could scratch it and make
a mark.
c
Layers of sediments built up on the sea
or lake bed. The bottom layers turned to
rock (sedimentation).
a
A mould
b
The leaf made an imprint in sediments.
Challenge
Challenge
3
a
a
Five million years old
b
Minerals in the water gradually replaced
the bones of the animals.
c
Nobody has ever seen any of the
animals alive.
d
The fossils they found were of animals
such as elephants and giraffes that need
water and trees and lots of vegetation.
e
Phosphate rich sandstone
Topic 3.3: Metamorphic rocks
and the rock cycle
Focus
1
a
2
Limestone → Marble
Sandstone → Quartzite
Shale → Slate
Granite → Gneiss
B
b
C
c
A
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
Practice
e
3
4
Is rock crystalline?
Yes
No
Does rock have a
banded appearance?
Rock is
sedimentary
Yes
No
Rock is
metamorphic
Rock is
igneous
Challenge
5
A: Erosion; B: Sedimentation; C: Pressure;
D: Metamorphic; E Intrusive
Challenge
5
Learners should draw something like this.
Make sure the order of processes is correct.
igneous rock:
granite
weathering
cooling
erosion
transportation
melting
deposition on seabed
sedimentation
heat
pressure
a
They use compost instead of artificial
fertilisers; they rotate their crops.
b
Providing natural predators of the pests
instead of killing pests with pesticides.
c
Farmers plant flowers and hedges near the
crops. The flowers and hedges attract the
predators which kill the pests.
d
Bird predators of snails: blackbirds,
thrushes and grouse; animal predators of
snails: mice, shrews and squirrels.
4 Food chains and food
webs
Topic 4.1: Food chains, food webs
and energy transfers
Focus
1
metamorphic rock:
quartzite
They can dig and break up the soil;
they can dig and mix in compost to add
organic matter and improve the texture;
they can water the soil regularly.
a
great white shark
sedimentary rock:
sandstone
jelly fish
burial
algae
Topic 3.4: Soil
Focus
1
sea turtle
The Earth’s crust consists of rocks. Rain
and ice break up the rocks. The small rock
particles become soil.
2
Any three from texture, organic matter,
water, air.
3
Sandy soil, clay soil, loam
Practice
4
7
a
The texture is dry and sandy. The colour
is yellowish.
b
No. There are no bits of dead leaves or
animals in it.
c
Sandy soil
d
No. There is no organic matter in the soil.
The soil is too dry and too hard.
small fish
plant plankton
b
fish eggs
prawn
The arrows show the direction in which
energy moves from one living thing to the
next living thing in the food chain.
Practice
2
a
Any two from:
fish eggs → jelly fish → sea turtle → great
white shark
algae → prawn → sea turtle → great
white shark
fish eggs → prawn → sea turtle → great
white shark
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
b
Plant plankton, algae
c
c
i
Small fish
ii
Jelly fish, prawn
iii
Sea turtle, great white shark
d
The Sun
e
Great white sharks are predators of the
sea turtle. If there were no more of them,
the numbers of sea turtles would increase
because no other animals in the food web
eat them. However, their numbers would
only increase if there was enough food for
them to eat.
Topic 4.2: Harm to food chains
and food webs
Focus
1
Challenge
3
a
Note: all food chains can start with
either the seeds or grasses. Any ten of the
following 16 food chains:
grass/seeds → ant →ant lion
grass/seeds → termite → spider
grass/seeds → termite → lizard →
sidewinder adder
grass/seeds → termite → spider → lizard
→ sidewinder adder
grass/seeds → termite → spider →
scorpion→ sun spider → lizard →
sidewinder adder
grass/seeds → beetle → lizard →
sidewinder adder
grass/seeds → beetle → sun spider →
lizard → sidewinder adder
grass/seeds → beetle → scorpion→ sun
spider → lizard → sidewinder adder
b
2
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a
Toxic
b
Accumulate
c
Pesticide
d
Environment
e
Mercury
a
True
b
False
c
False
d
True
Practice
3
sidewinder
adder
Most consumers eat more than one kind
of living thing. Producers are usually
eaten by many different herbivores or
omnivores. Most herbivores are eaten by
more than one carnivore or omnivore.
A food web shows all the possible food
chains a living thing can be part of in its
habitat.
a
Any reasonable suggestion, such as it
was released into the river by a factory or
mine; it washed in from soil runoff from
farmland sprayed with pesticides.
b
The heron
c
Sixty times more
d
i
lizard
sunspider
antlion
spider
scorpion
ant
termite
The quantity of chemical X increases
with each link in the food chain. This
means that the higher the living thing
is in the food chain, the greater the
quantity of chemical X it has.
beetle
grasses
8
seeds
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
ii
Each living thing in the food chain
eats more than one of the living
things below it in the food chain. So,
the greater the number of any kind
of living thing eaten, the greater the
quantity of chemical taken in. This is
because the chemical stays in the bodies
of the things that are eaten.
5 Forces and electricity
Topic 5.1: Mass and weight
Focus
a
A balance or scale
b
Grams (g) and kilograms (kg)
Challenge
c
Forcemeter
4
d
Newtons (N)
a
b
c
DDT was used to kill mosquitoes that
spread malaria; it was used to spray crops
to kill insect pests.
i
If crops (producers) are sprayed, they
will be covered with DDT.
ii
DDT does not break down in the
bodies of animals (they cannot
get rid of it), or very easily in the
environment. Herbivores that eat the
crops will take the DDT into their
bodies. The DDT will be passed to
carnivores that eat the herbivores.
i
ii
d
e
f
DDT is stored mainly in body fat.
Seals and polar bears have lot of
body fat to protect them from the
cold in the arctic. DDT also remains
in the environment for a long time
before it is broken down, so it can still
be absorbed from the surroundings.
The seals may have DDT in their
bodies. If people eat the seals, the
DDT will enter the people’s bodies
where it may cause cancer and other
serious diseases.
Because there was not enough DDT in the
three locusts to kill the frog, but the owl got
DDT from 9 locusts (3 locusts in each of 3
frogs). The DDT level was high enough to
kill the owl. The word that describes this is
accumulation.
Some birds would have died from eating
other animals that contained DDT. The
DDT made the bird’s eggshells weak, so
fewer chicks hatched.
1
2
Mass is the amount of matter in an object.
Weight is the amount of attraction on an
object caused by the force of gravity.
Practice
3
4
5
b and c are true; a and d are false.
Object
Mass
Weight
Brick
Bag of books
Bag of potatoes
Bag of cement
1 kg
2.5 kg
10 kg
40 kg
10 N
25 N
100 N
400 N
No, because you are adding to the weight.
Challenge
6
7
a
A forcemeter
b
30 N
c
3 kg
Mr Large will weigh 450 N on Planet Zogg.
If his mass is 90 kg on Earth, his weight will
be 10 × 90 = 900 N.
But since gravity is only half as strong on
Planet Zogg, his weight will be half of 900 N,
which is 450 N.
Topic 5.2: The effects of forces
Focus
1
Dichloro-diphenyl-trichloroethane
a
Changes the speed of an object.
b
Changes the shape of an object.
c
Makes an object move.
d
Changes the direction of a moving object.
Practice
2
9
a
The ball changes direction or stops moving.
b
The ball changes shape.
c
The ball moves.
d
The ball changes direction.
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
3
Practice
gravity
3
a
The control variable is the container of
water (this remains the same).
The independent variable is the number of
coins they put on the raft (this changes).
The dependent variable is whether the
container floats or sinks – this is what
they observe as a result of changing the
number of coins on the raft.
b
The mass of the raft was less than the
mass of water it displaced as a result of
the upthrust.
c
The mass of the raft and the coins was
more than the mass of water displaced as
a result of the upthrust.
d
The girls could make the raft wider or
longer or both (i.e. increased its area).
normal force
Challenge
4
a
b
Action with tennis
ball
Roll tennis ball
across floor
Roll tennis ball
across floor to the
wall.
Roll tennis ball
across the strip of
sandpaper
Bounce the tennis
ball on the floor or
against the wall
Press the tennis ball
down on the ground
with hand or foot
Effect of force
Make tennis ball
move
Stop the moving
tennis ball
Slow down the
moving tennis ball
e
Change the
direction of the
moving tennis ball
Change the shape of
the tennis ball
upthrust
Force diagram must include arrows
and labels for gravity, normal force and
applied force (pushing, rolling) and
possible friction (if learner draws the ball
rolling along sandpaper).
Challenge
3
a
Topic 5.3: Floating and sinking
b
Focus
1
2
gravity
When the ballast tanks are full of water,
the total mass of the submarine is more
than the mass of the water it displaces as
a result of upthrust.
gravity
An object will float if the mass of the object
is the less than, or equal to, the mass of water
displaced by upthrust.
An object will sink if the mass of the object
is greater than the mass of water displaced by
upthrust.
gravity
sea
gravity
ballast tanks
full of water
upthrust
upthrust
upthrust
10
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
4
c
a
They have a supply of tanks of
compressed air.
b
The time depends on how much food,
water and compressed air the submarine
has for the sailors in it. Usually the length
of time is 90 days.
c
The longest submerged submarine was
Submarine Warspite, which stayed
submerged for 111 days.
Topic 5.4: Different circuits and
circuit diagrams
A
Challenge
4
Focus
1
Component
B
a
A and B are parallel circuits and C is a
series circuit.
b
The lamps will shine more brightly in
circuit B because this is a parallel circuit.
In circuit C the electricity has to be shared
between all three lamps in a series circuit.
c
Lamp 3 will shine brightest. Lamps 1 and
2 have to share the electricity but lamp 3
gets the full strength.
d
Lamp 3 will not light up because the
switch is open and the circuit is broken.
e
Lamp 1 would come on but lamps 2 and 3
would not come on.
Symbol
3V
f
1.5V
This shows just one of the many possible
arrangements of the components in the
circuit.
Practice
b
No, the buzzer will not work because the
switch is open and therefore the circuit is
broken.
Topic 6.1: Reflection
a
Circuit A is a series circuit. Circuit B is a
parallel circuit.
1
b
The lamps will shine more brightly in
Circuit B. This is because in a parallel
circuit, the full strength of the battery
goes to each lamp.
Focus
A
t
en
cid
in
11
A 3V battery, a switch, a buzzer and
connecting wire.
ted
3
a
re
fle
c
2
6 Light and the solar
system
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
4
B
a
The top of the periscope is above the level
of the sea. By turning the periscope, the
man can see any ships that are in the area
(or any other sensible answer).
b
Seeing the stage at a concert, seeing the
game at a sports event, where there are
people standing in front of you who are
blocking your view.
d
cte
fle
re
in
cid
en
t
Topic 6.2: Refraction
Focus
C
1
The pencil is bent because of reflection/
refraction.
A ray of light passes from the pencil through
the water/air to the glass. The ray bends/
straightens when it passes through the glass to
the air/water and into our eyes.
We see the bent pencil as a trick/an optical
illusion.
2
A lens is a transparent piece of glass or plastic
with at least one straight/curved surface.
A convex lens makes things look bigger/
smaller because light rays bend inwards/
outwards as they leave the lens.
reflected
t
inciden
ec
re
fl
en
cid
in
ted
D
t
Practice
3
Practice
2
a
Diagram B shows a periscope.
b
Diagrams A and F are incorrect.
c
Make sure arrows are pointing in the right
direction and angles equal.
A
F
incident ray
reflected ray
incident ray
reflected ray
4
Challenge
3
12
a
She is using a periscope to see the bird’s nest.
b
Light from the bird’s nest travels through
the top window of the periscope to the
top mirror. Light reflects off this mirror,
down the periscope to the bottom mirror.
It reflects off the bottom mirror through
the viewing window to Zara’s eyes.
a
Convex lenses
b
Convex lenses bring distant rays to a focus
in our eyes. So binoculars allow us to see
far away things much larger.
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CAMBRIDGE PRIMARY SCIENCE 6: TEACHER’S RESOURCE
Challenge
5
A mirage is caused by refraction. Light travels
through warm air at a different speed than
through cool air. This causes people to see
objects in a different position from where the
objects really are. In a hot desert the layer of
air above the sand is much hotter than the
air further up. Sometimes refraction causes
a distant surface to appear wet. This is why
people in a desert claim they see water in the
distance. But it is an optical illusion.
b
An ‘Earth day’ is 24 hours and an ‘Earth
year’ is 365¼ days or 8766 hours.
c
Mars, Jupiter, Saturn, Uranus and
Neptune. All these planets are further
from the Sun than Earth and therefore
take longer to complete their orbits
around the Sun.
d
Mercury, because this planet is the closest
to the Sun.
e
The scale is very incorrect. In reality the
Sun is far larger than any of the planets.
The distance between the planets and
the Sun is much larger than shown on
the diagram.
Topic 6.3: The solar system
Focus
1
a
4
Sun
a&b
waning
crescent
Jupiter
Mercury
new
Moon
Sun
Mars
b
Turning on an axis; moving in an orbit
around the Sun.
a
The movement in an orbit around the
Earth.
b
29.5 or 29½ days
c
Between 4 and 7
a
Saturn
Uranus
Jupiter
Mercury
Venus
Mars
Neptune
Earth
13
full
Moon
waxing
crescent
Neptune
Practice
3
Earth
Saturn
Venus
waning
gibbous
Uranus
Earth
2
third
quarter
waxing
gibbous
first
quarter
Challenge
5
a
Planet
Earth
Mars
Jupiter
Distance from 150
Sun
million
km
240
million
km
800
million
km
Time taken
to make one
turn on axis
24
hours
25
Earth
hours
10
Earth
hours
Time taken
to make one
orbit around
the Sun
365¼
days
687
Earth
days
12
Earth
years
Number of
moons
1
2
79
Lowest
temperature
in winter
−50 °C
−125 °C −153 °C
What is
planet
made of?
Rocks
Rocks
Gases
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b
The time becomes longer from Mars
to Jupiter.
This is because the distance from the Sun
becomes longer from Mars to Jupiter, so it
takes longer to complete an orbit.
c
On Earth there is water and oxygen.
d
It is formed of gases. There is no water
or oxygen.
The temperature falls to −153 °C
e
The length of day and night would be almost
the same as on Earth. We would see the
sunrise and sunset.
6
a
Pisa, Italy in 1564.
b
He used the recently invented telescope.
c
He discovered the craters on the Moon,
sunspots on the Sun and the phases
of Venus.
d
Galileo said that the Sun was the centre
of the solar system. Up until then the
Church told people that the Earth was at
the centre and the other planets and the
Sun moved round the Earth. The Church
arrested Galileo and made him stay under
house arrest for the rest of his life for
going against their teachings.
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