Year 3 science · Key Stage 2 · Light

Year 3 light: shadows, reflection and sun safety explained

In Year 3, children learn that we need light to see, and that dark is simply the absence of light. They notice that light bounces off surfaces, learn how to protect their eyes from bright light and the sun, and find out that shadows form when an opaque object blocks light. They also look for patterns in how the size of a shadow changes.

Light, reflection and shadows, explained

The first idea sounds obvious but needs careful thought: we see things because light gets into our eyes. Some objects, like the sun, a torch or a candle flame, give out their own light and are called light sources. Most things we see, from a book to a tree to the moon, are not light sources at all; we see them because light from a source bounces off them and into our eyes. Dark is not a thing that exists by itself. It is what we have when there is no light. A room with the lights off and the curtains drawn is not full of dark; it has had the light taken away.

That bouncing is called reflection. Children notice that light is reflected from all surfaces, but shiny, smooth ones such as mirrors, metal and still water reflect it in a way that gives a clear image. A rough surface scatters the light in many directions, so we see the object but not a picture of ourselves in it. Mirror games, such as reading words reflected in a mirror or bouncing a torch beam off a mirror onto a wall, are popular ways to explore this. Reflective strips on clothing and bikes are a good everyday example: they send light from car headlights back towards the driver.

Children also learn that light from the sun can be dangerous, and that there are ways to protect their eyes. The key safety message is that you should never look directly at the sun, even with sunglasses. Sunglasses and sun hats help against bright daylight and glare, but they do not make looking at the sun safe. The same goes for a very bright torch or laser pointer. Looking at very bright light can damage the eye.

Shadows are the last big topic. A shadow forms when light from a source is blocked by an opaque object, one that light cannot pass through. Transparent materials, such as clear glass, let almost all light through and make very faint shadows or none. Translucent ones, like tissue paper, let some through and make a pale shadow. Using a torch and a card shape, children look for patterns: the closer an object is to the light source, the bigger its shadow. Out of doors, shadows are long in the morning and the evening, when the sun is low, and short around midday when it is high in the sky.

Words your child will hear

Light source: Something that gives out its own light, such as the sun, a torch or a lamp.
Reflect: When light bounces off a surface. It is how we see things that are not light sources.
Opaque: Does not let any light through, so it makes a dark shadow.
Transparent: Lets light through so you can see clearly through it, like clear glass.
Translucent: Lets some light through but you can’t see clearly through it, like tissue paper.
Shadow: The dark shape made when an opaque object blocks light.
Dark: The absence of light.

What the National Curriculum says

In Year 3, pupils should be taught to:

Recognise that they need light in order to see things and that dark is the absence of light
Notice that light is reflected from surfaces
Recognise that light from the sun can be dangerous and that there are ways to protect their eyes
Recognise that shadows are formed when the light from a light source is blocked by an opaque object
Find patterns in the way that the size of shadows change

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

Try it: how does the distance from the torch change a shadow?

A card figure 10 cm tall stands between a torch and a wall. The torch is always 100 cm from the wall. How does the shadow’s height change as the figure is moved closer to the torch?

Make a prediction. “I think the nearer the figure is to the torch, the bigger the shadow will be, because it blocks more of the light.”
Set up a fair test. Change only the distance of the figure from the torch. Keep the torch in the same place, use the same figure, and measure the shadow height on the wall in centimetres each time. Darken the room.
Record the results in a table. These are sample results; real ones are usually a little less tidy. At 100 cm the figure is standing right against the wall.
```
Torch to figure | Shadow height
100 cm          | 10 cm
50 cm           | 20 cm
25 cm           | 40 cm
20 cm           | 50 cm
```
Find the pattern. As the figure moves towards the torch, the shadow gets taller: 10 cm, 20 cm, 40 cm, then 50 cm. The closer the figure is to the light source, the bigger the shadow.
Use the pattern to predict. A figure 40 cm from the torch sits between the 50 cm test (a 20 cm shadow) and the 25 cm test (a 40 cm shadow), so its shadow should be somewhere between 20 cm and 40 cm tall.

The closer the card figure is to the torch, the larger its shadow, because light spreads out from the torch, so a figure near the torch blocks a bigger share of it. At 100 cm, with the figure against the wall, the shadow is the same height as the figure (10 cm), and at 20 cm it is five times as tall (50 cm). A figure 40 cm from the torch should make a shadow between 20 cm and 40 cm tall.

Common mistakes and how to help

Thinking we see because light comes out of our eyes

We look at things, so it feels as if something goes out from the eye. Children also think we can see in the dark if we try hard.

What helps: In a dark cupboard or a room with the curtains closed, nobody can see anything, however hard they look. Light has to enter the eye. Show that a torch beam only lights up things it hits.

Believing shiny or bright-looking things, like the moon or a mirror, make their own light

The moon glows in the night sky and a mirror appears to light up when light hits it.

What helps: Ask “Would the moon shine if the sun were switched off?” A light source makes light; the moon and a mirror only reflect it. Check with a mirror in a dark room.

Thinking the closer an object is to the light, the smaller its shadow

Children may expect an object that is “more lit” to have less shadow, or confuse the object’s distance from the wall with its distance from the torch.

What helps: Try it. Hold a hand close to a torch and then far away, with the wall at the same distance. A close hand makes a big, blurry shadow; a far one makes a smaller, sharper shadow.

Thinking sunglasses make it safe to look at the sun

Dark lenses feel as if they take away the glare, so people trust them.

What helps: The rule is simple: never look directly at the sun, with or without sunglasses. Sunglasses and hats help with brightness and glare, but they are not for looking at the sun.

How to help at home

Torch and shadow puppets. In a dim room, make shadows with a torch and some card shapes. Move the shape closer to and further from the torch and see how the shadow changes. Try tissue paper, a clear plastic cup and a book to compare how much light each one lets through.
Dark cupboard test. Put a toy in a closed cupboard or a big box and ask whether you can see it. Open the door a crack and ask what changes. Talk about where the light is coming from and where it goes.
Mirror mission. Use a small mirror to bounce torchlight onto a target on the wall, or to read a word backwards. Never aim a beam at anyone’s eyes.
Track a shadow in the garden. Mark the end of a fence post or a stick’s shadow with a stone in the morning, at lunchtime and in the afternoon, and see how the length changes. Remember sun cream and a hat, and never look at the sun.

Everything in Year 3 science

Updated 20 October 2026.