Lesson 9: Eyeballs

We are going to make an eyeball model using a balloon. This experiment should give you a better idea of how your eyes work. The way your brain actually sees things is still a mystery, but using the balloon we can get a good working model of how light gets to your brain.


Download the student worksheet that goes with this lesson.

When the balloon is focused on the candle, this is your normal vision. When you squish the balloon from the top, the image becomes distorted and the focal point of the lens places the image in front of the retina (making the image blurry). This is a condition called nearsightedness. Farsightedness is when you squish the balloon together to make it taller, and the image actually focuses beyond the back of the eye.