Year 4 science · Key Stage 2 · Animals, including humans

Year 4 digestion, teeth and food chains: a guide for parents

In Year 4 science, children follow food on its journey through the human body, learn the names and jobs of the different teeth, and then step outside the body to look at how living things get their food. They describe the simple functions of the main parts of the digestive system, identify types of teeth, and build and read food chains using the words producer, predator and prey.

Digestion, teeth and food chains, explained

Digestion is the process of breaking food down into pieces small enough for the body to absorb and use. Children learn the main parts in order. Food is chewed by the teeth and mixed with saliva in the mouth, with the tongue helping to move it around. It is squeezed down the oesophagus (the food pipe) to the stomach, where it is churned and mixed with juices that break it down further. In the small intestine, useful substances from the food pass into the blood. In the large intestine, most of the water is taken back into the body, and what is left over leaves the body as waste. The small intestine is actually longer than the large one: it is narrower, which is why it has that name.

Teeth have different shapes because they do different jobs. Incisors at the front are flat and sharp for cutting and biting. Canines, the pointed teeth next to them, are for tearing. Premolars and molars at the back are broad and bumpy for crushing and grinding food. Children have 20 baby teeth, which are gradually replaced, and adults usually have up to 32. Many schools compare human teeth with those of a meat eater and a plant eater, noticing that the pointed canines of a dog or cat are large while the flat grinding molars of a cow or horse are broad. Children also learn what harms teeth, such as sugary food and drinks left on the teeth, and how brushing, flossing and visiting a dentist help.

Food chains show who eats what in a habitat. Every food chain starts with a producer, a plant or other living thing that makes its own food using energy from the sun. Animals cannot do this, so they must eat other living things. A predator hunts and eats other animals, and an animal that is hunted is its prey. In a longer chain, the same animal can be a predator for one animal and prey for another. The arrows in a food chain point from the food to the animal that eats it, showing the direction that energy and food move.

Children are asked to both construct and interpret food chains. Constructing means starting from a description (“snails eat lettuce, thrushes eat snails”) and writing the chain in order. Interpreting means reading a given chain and answering questions about it, for example what would happen to the other animals if one of them disappeared. This is a first step towards understanding that living things in a habitat depend on one another.

Words your child will hear

Digestion: Breaking food down into tiny pieces the body can use.
Oesophagus: The tube, also called the food pipe, that carries food from the mouth to the stomach.
Small intestine: The long, narrow tube where useful substances from food pass into the blood.
Incisor, canine, molar: Teeth for cutting, tearing and grinding. Premolars sit between canines and molars.
Producer: A living thing, usually a plant, that makes its own food using energy from the sun.
Predator: An animal that hunts and eats other animals.
Prey: An animal that is hunted and eaten by a predator.

What the National Curriculum says

In Year 4, pupils should be taught to:

Describe the simple functions of the basic parts of the digestive system in humans
Identify the different types of teeth in humans and their simple functions
Construct and interpret a variety of food chains, identifying producers, predators and prey

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

A worked example

A blue tit eats caterpillars. Caterpillars eat cabbage leaves. A sparrowhawk catches blue tits. Write the food chain, then label the producer, the predators and the prey.

Start with the producer. A cabbage leaf is a plant that makes its own food, so it goes first in the chain.
Next comes the animal that eats the plant: the caterpillar. Then the animal that eats the caterpillar: the blue tit. Last is the animal that eats the blue tit: the sparrowhawk.
Draw arrows from each living thing to the one that eats it, because the arrow means “is eaten by” and shows the direction food moves.
```
cabbage leaf → caterpillar
  → blue tit → sparrowhawk
```
Label the roles. The cabbage leaf is the producer. The caterpillar is prey for the blue tit. The blue tit is a predator of caterpillars and also prey for the sparrowhawk. The sparrowhawk is a predator.
Interpret: if a disease killed most of the caterpillars, the cabbage would be eaten less, and the blue tits would have less food, so fewer blue tits might survive, leaving the sparrowhawk with less to eat.

Cabbage leaf, then caterpillar, then blue tit, then sparrowhawk. The cabbage leaf is the producer. The blue tit is both a predator (of caterpillars) and prey (of the sparrowhawk).

Common mistakes and how to help

Drawing the arrows in a food chain the wrong way

Children read an arrow as “eats”, so they point it from the predator to the prey, as if the hawk were moving towards the blue tit.

What helps: Say the arrow as “goes into” or “is eaten by”. Ask “Where does the food go?” and follow it with your finger.

Thinking digestion only happens in the stomach

The stomach is the best-known part of the digestive system, so children assume everything happens there. Digestion actually begins in the mouth, and most useful substances pass into the blood in the small intestine.

What helps: Ask your child to trace a mouthful of food from start to finish, saying what happens at each place. Try a cracker held in the mouth: after a minute it begins to taste slightly sweet as saliva starts to break it down.

Thinking all teeth do the same job

Children see teeth as a single row of white shapes. Everyday chewing does not make it obvious that the front teeth bite and the back teeth grind.

What helps: Look in a mirror and bite into an apple slice. Notice which teeth cut and which crush. Link tooth care to all of them, including the hard-to-see back teeth.

Believing a predator can never be prey, or that the top of a food chain is always the biggest animal

Early examples show a big predator at the end. Children then label every animal in a chain as one or the other.

What helps: Use a three-animal chain. Ask which animal is eaten and also does the eating (the blue tit in the example). A small animal, such as a ladybird eating aphids, can still be a predator.

How to help at home

Trace a meal. At dinner, ask your child to describe the journey of one mouthful: teeth, tongue, oesophagus, stomach, small intestine, large intestine. A drawn body outline on a large sheet of paper makes a good, simple map.
Look at teeth in a mirror. Count and name the types of teeth you can see. Which ones do you use to bite a sandwich, and which to chew a carrot? Brushing for two minutes, twice a day, is the habit schools usually promote.
Build food chains from the kitchen. Pick a food and work backwards. Cheese on toast: the cheese is made from milk, which comes from a cow, which eats grass. Write it as grass → cow → human and ask which is the producer. Then try a bird visiting your garden feeder, which might eat seeds from a plant.
Compare animal teeth. Look at pictures of a cat, a sheep and a rabbit in a library book. Ask which animal has sharp, pointed teeth and which has flat ones for grinding, and what that suggests about what each animal eats.

Builds on

Year 3: Nutrition, skeletons and muscles

Leads on to

Year 5: Human growth and puberty

Everything in Year 4 science

Updated 20 October 2026.