About your eyes

We need light to see things. If you stand in a room which is completely dark, you can't see any thing at all. When you look at an object, you see the light that comes from it. The light travels from the object into your eyes.

Look at your eyes in a mirror. The black dot in the middle of each eye is called the pupil. It is like a window that lets light into the eye. Around the pupil is a coloured ring called the iris. The iris can be different colours – brown, blue, green. The iris can change size so that the pupil becomes bigger or smaller. When the light is bright, the pupil shrinks in order to reduce the amount of light coming into the eye. When the light is dim, the pupil gets larger in order to let in as much light possible.

If you were to cover one of your eyes with hand, you would still be able to see quite well. So why do you have two eyes?

One reason is that you can see more to each side of you with two eyes than you can with one eye. Because your eyes are placed on either side of your nose, each eye sees a slightly different picture. When you look at an object with both eyes, your brain uses these two pictures to decide how near or far away the object is. It is much easier to catch a ball if you have both eyes open than if you cover one eye with your hand.