Year 3 science · Key Stage 2 · Animals, including humans

Year 3 animals including humans: nutrition, skeletons and muscles

In Year 3, children learn that animals, including humans, cannot make their own food and must get the right types and amounts of nutrition from what they eat. They also find out that humans and some other animals have skeletons and muscles, and that these do three jobs: support, protection and movement. It builds on Year 2 work on growing up, survival needs and staying healthy.

Nutrition, skeletons and muscles, explained

The first big idea is a contrast with plants. A plant makes its own food using light, but an animal cannot, so every animal has to eat to get the energy and materials it needs. Children look at what different animals eat, including pets they know, and see that a diet suits the animal: a rabbit and a cat need very different food. For humans, the focus is on eating the right types and amounts. Many schools introduce the main food groups and what they do, for example: carbohydrates such as bread, rice and potatoes for energy; protein such as fish, eggs and beans for growth and repair; a little fat, which also gives energy; and fruit and vegetables, which give vitamins and minerals. Fibre and water matter too. Children design a healthy meal or compare lunch boxes, and talk about balance rather than about “good” and “bad” foods.

The second idea is that humans and many other animals have a skeleton. In humans it is a framework of bones inside the body, and other animals with a backbone, such as fish, birds and cats, have one too. The skeleton does three jobs. It supports the body, so we can stand upright instead of flopping like a jellyfish. It protects soft organs: the skull protects the brain, the ribs protect the heart and lungs, and the backbone protects the spinal cord. And it works with muscles to allow movement. Children learn to name main bones such as the skull, ribs, backbone (spine), pelvis, arm and leg bones, and they may meet the names of some, like the femur or humerus.

Muscles are the other half of movement. A muscle can only pull, never push. It does this by getting shorter, which is called contracting. Muscles are joined to bones, and when a muscle contracts it pulls the bone, which moves at a joint. To straighten again, a second muscle on the other side pulls the opposite way, so muscles work in pairs. In the arm, one muscle bends it and another straightens it. Children can feel this in their own upper arm as they lift a heavy book.

Schools commonly sort animals into those with and without skeletons. Worms, slugs and jellyfish have no bones at all; crabs and insects have a hard skeleton on the outside. Children compare how these animals move and what would happen if humans had no skeleton. The point is that the children use evidence from observation to link structure to function: the way a body is built relates to how it lives and moves.

Words your child will hear

Nutrition: The food and drink an animal takes in to stay alive and healthy.
Nutrient: A substance in food that the body needs, such as protein or vitamins.
Skeleton: The framework of bones in a body.
Muscle: Body tissue that gets shorter to pull on bones and make parts of the body move.
Joint: A place where two bones meet, such as the elbow or knee, which lets the body bend.
Protect: To keep safe from harm, as the skull protects the brain.
Balanced diet: Eating a mixture of foods in the right amounts.

What the National Curriculum says

In Year 3, pupils should be taught to:

Identify that animals, including humans, need the right types and amount of nutrition, and that they cannot make their own food; they get nutrition from what they eat
Identify that humans and some other animals have skeletons and muscles for support, protection and movement

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: what if humans had no skeleton?

Explain what would happen if humans had no skeleton, using what you know about support, protection and movement.

Start with the three jobs of a skeleton: support, protection and movement. Organise the answer by taking each in turn.
Support. Feel your spine and legs. Without bones the body would have no firm frame and would collapse on the floor, like a jellyfish out of water. We could not stand, sit up or hold our head up.
Protection. Tap gently on your skull and feel your ribs as you breathe in. Without a skull and ribs, the brain, heart and lungs would be soft and easily damaged by a bump or a fall.
Movement. Muscles can only pull. Without bones for the muscles to pull on there would be nothing to move, so we could not walk, run or pick things up. Animals without a skeleton, such as worms and slugs, move in a very different way, by squeezing and stretching their whole bodies.
Finish with a sentence that links the evidence to the answer.

Without a skeleton, humans could not stand up because nothing would support the body, the brain, heart and lungs would be unprotected, and muscles would have no bones to pull on to make us move. A skeleton and muscles work together to support, protect and move us.

Common mistakes and how to help

Thinking animals can make their own food like plants

Having just learnt that plants make their own food, children may assume all living things do, or that animals can live on water and sunshine.

What helps: Say the contrast clearly. Plants use light to make food; animals have to eat plants or other animals. A rabbit eats grass and a fox mostly eats other animals, but neither can make food inside its body.

Thinking that bones are hard, dry and dead

The bones we see in pictures or in museums are dry and lifeless, so children expect those inside us to be the same.

What helps: Bones are living and they grow. A broken bone can mend itself. Ask why your child needs bigger shoes and longer trousers each year: it is because their bones are growing.

Believing muscles push bones as well as pull them

When we push a door it feels as if the muscle is pushing, so children assume it does.

What helps: Feel your upper arm as you bend and straighten your elbow. Different muscles tighten each time. Muscles only ever pull, and work in pairs to move a bone back.

Thinking a healthy diet means avoiding some foods completely or eating as much as possible of one

Messages about “healthy” and “unhealthy” foods are often simplified. Children may think a food group is bad or that more of a good food is always better.

What helps: Talk about the right types and amounts. Every food group has a job, and a balanced diet is a mixture. Foods high in sugar or fat are fine in small amounts but should not be the main part of the diet.

How to help at home

Sort the shopping. When you unpack the shopping, ask your child to sort it into food groups, such as foods that give energy, foods that help the body grow and repair, and fruit and vegetables. Then plan a balanced dinner from what you have.
Feel your own skeleton. Find your skull, ribs, spine, elbows and knees by touch. Ask which bones are protecting something and which are mostly for moving.
Muscle watching. Feel the muscle at the front of the upper arm tighten as you bend your elbow, and then the muscle at the back tighten as you straighten it against a table top. Use words such as “contract” and “pull”. Do the same for a leg.
Make a model hand. Cut a card hand with finger shapes and stick short pieces of straw on each finger. Thread string through the straws and fix it at the fingertip. When you pull the string, the finger bends, which shows how a muscle pulls on a bone. Use blunt-ended scissors, with an adult nearby.
Pets and wildlife. Compare what a pet and a wild bird eat and how each moves. Only feed pets their normal food. When looking for minibeasts such as worms and snails in the garden, put them back where you found them and wash your hands after.

Builds on

Year 2: Growing up and staying healthy

Leads on to

Year 4: Digestion, teeth and food chains

Everything in Year 3 science

Updated 20 October 2026.