What are pupils?

Pupils are the black circles in your eyes that help you see better in different lights.

Imagine you're playing with a flashlight at night. When it's dark, you turn the flashlight on, suddenly, everything becomes brighter. Your pupils work like that flashlight. They get bigger when it’s dark so more light can come into your eye, and they shrink when it’s bright so less light comes in.

Think of your pupil as a door in your eye. When the room is dim, the door opens wide to let in more light. But when the room is bright, like outside on a sunny day, the door closes smaller so you don’t get blinded by all that light.

You can see this happen if you look at someone’s eyes when they go from a dark room to a bright one, their pupils will shrink quickly, like a cat's eyes when it sees a flash of light.

Sometimes your pupils even change size when you're excited or scared, just like how your heart beats faster when you're happy or nervous!