Grade 3 Science — Review – Unit 1
Unit 1: Skeletons, Muscles, Animal Groups & Scientific Enquiry
Part A — Bony Riddles 🦴
Use the word bank to solve each riddle. Each word is used only once.
skull
ribs
hip
leg bones
jaw
1. I am a curved cage that protects your heart and lungs. What am I?
____________________________________________________________
2. I am the hard, round bone that protects your brain. What am I?
____________________________________________________________
3. I move up and down when you chew your food. What am I?
____________________________________________________________
4. I am wide bones that connect your backbone to your legs, and help you sit and stand. What am I?
____________________________________________________________
5. I am long and strong, and I help you walk, run, and jump. What am I?
____________________________________________________________
6. The skeleton helps your body move. Name two other jobs the skeleton does. [2 marks]
____________________________________________________________
____________________________________________________________
Part B — Skeleton Models
A model of a skeleton, like the one your teacher uses in class, is a useful teaching tool — but it is not
exactly like a real skeleton.
(a) Tick TRUE or FALSE for each sentence about a classroom skeleton model.
Statement
A model skeleton is usually made
of plastic, not real bone.
A model moves in exactly the
same way as a real human
skeleton.
True
False
A model can be used to show
where bones are and how joints
bend.
(b) Circle the correct word to complete the sentence.
Teachers use a skeleton model in class because it is bigger / smaller than some real skeletons, and it
is easier / more difficult to carry around and use to demonstrate movement than a real one.
Part C — Muscles at Work 💪
Muscles work together with the skeleton to help the body move.
(a) What do muscles attach to? Circle one.
Skin
Bones
Nerves
(b) Fill in the missing word using the word bank. Choose one.
pushing
contracting
stretching
When you bend your arm, one muscle shortens by ...................................... while the other one
relaxes.
(c) In your own words, explain why muscles are important for the human body.
____________________________________________________________
____________________________________________________________
Part D — Animal Groups
Look at the animals below, then answer the questions.
rabbit
crab
butterfly
cat
🪸
worm
frog
jellyfish
bee
7. The rabbit and the cat both have a backbone inside their bodies. What is the name of this animal
group?
____________________________________________________________
8. Which TWO animals above do NOT have a backbone at all? [1 mark]
____________________________________________________________
9. Circle ONE feature (other than having a backbone) that you could use to sort these animals into
groups.
Number of legs
Favourite food
Colour of their fur
10. Which animals above have a hard outer case called an exoskeleton instead of bones inside their
body? Name at least one.
____________________________________________________________
11. Complete the sentence: Having an exoskeleton helps an animal because it...
____________________________________________________________
____________________________________________________________
Part E — Fair Tests & Patterns 🔬
Priya wants to find out if arm length affects how far someone can throw a beanbag. She measures the
arm length and throw distance of three children.
(a) Use the information below to complete the table.
Arm Length: Sam: 50 cm Ravi: 45 cm Lily: 40 cm
Child
Arm length (cm)
Throw distance (cm)
Sam
180
Ravi
160
Lily
140
(b) Whose beanbag travelled the shortest distance?
____________________________________________________________
(c) What pattern do you notice between arm length and throw distance? Complete the sentence,
choosing from the box.
increases
decreases
stays the same
As arm length gets longer, throw distance ......................................................
(d) What type of scientific enquiry is this? Circle one.
Pattern seeking
Fair test
Research
(e) Priya predicts that a child with a 35 cm arm length will throw the beanbag 200 cm. Is her
prediction sensible? Circle Yes or No, then explain your answer.
Yes
No
____________________________________________________________
Part F — Fair Measuring
12. A scientist measures a plant's height using a ruler marked in centimetres, instead of using hand
spans. Which sentence best explains why this is a better way to measure?
A ruler is more colourful.
A centimetre is the same length for everyone, everywhere.
ruler is easier to lose.
A
13. A student wants to find out how plants grow in different amounts of sunlight. Which of these
would be the BEST way to research this question before starting an experiment?
a comic book
a story book about space
the internet or a science book
Part G — Staying Safe with Medicine 💊
(a) Complete the sentences below using the words from the box.
stay safe
guessing
following instructions
have fun
Medicines should always be used safely by .......................................................... given by an adult you
trust. This is important because it helps you ..............................................................
Part H — Infectious Diseases
sunflower
butterfly
rabbit
(a) True or false: Both animals and plants can catch infectious diseases. Circle one.
True
False
(b) Name ONE infectious disease that can make people unwell.
____________________________________________________________
(c) Explain in your own words what the word ‘infectious’ means.
____________________________________________________________
bee
Answer Key (for checking your work)
Part A: 1. ribs 2. skull 3. jaw 4. hip 5. leg bones 6. any two of: protects organs, supports the
body/gives it shape, helps make blood cells
Part B: (a) True, False, True (b) bigger / easier (accept teacher's classroom context)
Part C: (a) Bones (b) contracting (c) muscles let bones move, help us breathe, help the heart pump,
protect the body
Part D: 7. Vertebrates (animals with a backbone) 8. crab and butterfly (or bee) 9. Number of legs
10. crab (and butterfly/bee) 11. protects the soft body inside / acts like armour
Part E: (a) Sam 50cm, Ravi 45cm, Lily 40cm (b) Lily (c) increases (d) Pattern seeking (e) No —
accept any reasonable explanation, e.g. the pattern would suggest a shorter throw, not a longer one
Part F: 12. A centimetre is the same length for everyone, everywhere. 13. the internet or a science
book
Part G: following instructions; stay safe
Part H: (a) True (b) e.g. flu, chickenpox, common cold (c) a disease that can spread/be passed from
one living thing to another
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