Eyeball

Look no further ... Bill Nye is on the ball - the eyeball.   For their small size, your eyes do an important job. By working with your brain, your eyes can tell the   difference between thousands of different colors. They can follow a fast-moving hockey puck across the   ice. They are even sending messages to your brain about what you're reading right now. Eyes work a lot   like a camera. They take in light, focus light, and make images. With help from the brain, your eyes help   understand the world around you.   Light bouncing into your eye passes through an opening called the pupil. If you look in the mirror, your   pupil is the black area in the middle of your eye. The pupil can open or close, depending on the brightness   of the light. After passing the pupil, the light is focused onto the back of your eye by the lens, a thin layer   of cells. On the back of your eye are special cells called rods and cones that are sensitive to light. These   cells send electrical messages to your