Look into my eyes!
The pupil, the iris, the lens and the back of the eye, and how your eyes and brain work together to see. With a pupil-watching experiment.
Read
Light goes into your eye through a little black hole in the middle: the pupil. The coloured ring around it is the iris.[1]
The iris makes the pupil smaller in bright light and bigger in dim light.[2]
At the front of the eye is a clear dome called the cornea. Inside is the lens. Together they bend the light to make a sharp picture at the back of the eye.[1]
The back of the eye is the retina. Special cells there turn light into messages. The messages go along the optic nerve to your brain, and your brain makes the pictures you see.[1]
Some cells in your eye help you see when it is dim, but only in grey. Other cells see colours, but they need more light.[2]
Some people wear glasses. For some, things far away look blurry. For others, things close up look blurry.[6]
Try it: Watch the pupil change
You need
- A partner
- A normally lit classroom (no torches or lamps)
- A pencil and the results table
Safety
Never shine a torch or any light into someone's eyes, and never look at the Sun. Don't touch or poke eyes. Be gentle and kind: only watch.
What to do
- Sit facing your partner. Look at the black pupil in the middle of their eye. Draw how big it is.
- Your partner covers both eyes with their hands and counts slowly to 20.
- Your partner takes their hands away and looks at you. Watch the pupil closely straight away!
- What happens to the pupil in the first few seconds? Draw it again.
- Swap jobs and try it again.
Play: Big pupil or small pupil?
Read each card. Is it bright or dim there? Will the pupil be small or big?
Your best score is kept only on this device. Nothing is sent anywhere.
Quiz
Other ages: Ages 10–11 · Ages 15–16