Video and lesson investigations on the topic of eyes. Key concepts include:
- Light travels into the eyes.
- It gets into the eye through a hole at the front.
- The size of the hole changes to let in more or less light.
- When light hits the back of the eye, the brain interprets what the eyes see. Light enters through the pupil. The iris controls the size of the pupil.
- The retina at the back of the eye contains nerve ends which send messages to the brain. Light shining on the eye triggers the reflex of the pupil to constrict. Darkness, in turn, causes the pupil to open up so that it can let in more light. The function of the pupil is to let in no more light than the eye can tolerate, but enough to let the eye work.
- The size of the pupil is controlled by a ring of muscles around the iris (the colored part of the eye).
- The inside of the eye is filled with a thick, jelly-like material that helps to make the eyeball round, and transmits images through the eye.