A kindergarten lesson on the human eye needs to be informative yet creative. While it is important to impart information on both the parts and function of the eye, it is vital that you avoid getting bogged down in excessive detail and description. At this stage in their education, kindergartners don't need to know every muscle and blood vessel involved in the sight process; that will come in later years. For now, let the lesson satisfy their curiosity about the parts that make up the eye and the function of each.
To Begin the Lesson
Begin the lesson by asking a few questions: Which part of your body do you use to see? Which part of your body do you close at night when you go to sleep? Which part of your body tells you what color something is or what someone looks like? Explain that the eye is an important part of the body and that, without it, life would be much more difficult. Holding up a pingpong ball, explain that the eye is round and about the same size as the ball in your hand; however, the eye is made up of many different parts, some of which cannot be seen because they are either inside the eye or on the back side of the eye.
The sclera is the white part of the eye that you can see when you look in the mirror. Give each student a small mirror and have them locate the sclera of their eyes. Point out that the red lines they see are blood vessels, which are like straws that carry blood to the sclera to keep it healthy.
The cornea is an invisible skin that rests on top of the colored part of the eye. Inform the students that the cornea is clear like glass and therefore not able to be seen. Explain that the cornea is responsible for helping the eye to see and to focus so images are not blurry.
The iris is the colored part of the eye. It has the duty to control how much light goes into the eye. Allow the students a few minutes to look in their mirrors and to discuss what color their irises are.
The black dot in the center of the eye is the pupil. The pupil is a hole in the iris that allows light to enter the eye, a lot like window blinds that open wide to let more light in or close tight to allow less light in. (If you have blinds in your classroom, take the time to demonstrate by opening and closing the blinds). Instruct the students to look in their mirrors and focus on their pupils. Turn out the lights for a couple of moments, then flip them back on. Ask the students what they noticed about their pupils. If they were watching closely, they will have seen their pupils shrink drastically to keep out excess light when the lights came back on.
The lens sits directly behind the iris. When light comes in through the pupil, it bounces off the lens, much like light reflecting off a mirror, and focuses the light onto the retina, which is located at the back of the eyeball.
The retina is like a movie screen, but the picture it receives from the lens is upside down and in a language the brain doesn't understand. The retina's job is to translate the information into a language the brain will understand.
The optic nerve is a long cord that acts as a messenger from the eye to the brain and carries the information of the upside down image that is translated by the retina. Hold up a paddleball set and ask the students to imagine that the ball is their eye and the paddle is their brain. The string that connects the two is the optic nerve. Explain that the optic nerve is so long that if the eye were to pop out of its socket, the eyeball would hang down to the chin.
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