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Experiments: Sight

What Kids Learn

Here are three fun experiments that help teach kids about vision. The first two experiments show kids how our eyes work together as a team. Two eyes really are better than one! The third experiment teaches kids about a funny thing that can happen when some receptors in our eyes get tired.

Experiments 1 and 2: Depth Perception

Two eyes give us more depth perception, which is the ability to judge how near or far objects are.

What You Need for Experiment 1

  • Two pencils

What to Do

  1. Have the child hold a pencil lengthwise (on its side) in each hand.
  2. Tell the child to close one eye and try to touch the erasers together. Did he or she miss?
  3. Now, tell the child to try it with both eyes open. Voila! Two eyes give you better depth perception.

What You Need for Experiment 2

  • Five pennies
  • Small paper cup or rinsed-out yogurt cup
  • A table where you and the kid can sit

What to Do 

  1. Put a cup in front of, and about 2 feet away from, the child.
  2. Ask the child to close one eye.
  3. Hold one of the pennies in the air about 18 inches above the table. Move it around slowly.
  4. Tell the kid that you'll drop the penny whenever he or she says, "Drop it!" The idea is for the kid — with one eye closed — to judge when the penny is over the cup so the penny will drop into the cup.
  5. Give the kid five tries with one eye closed, then five tries with both eyes open. Which way worked best?

Experiment 3: The Red, White, and Blue

The receptors in our eyes that are sensitive to certain colors can get tired. When they don't work as usual, you may see an afterimage in colors that are different from the image you were looking at. An afterimage is when the eyes see something that isn't there.

 What You Need

  • The image of the yellow and blue flag below

What to Do 

  1. Tell the child to stare at the yellow and blue U.S. flag for about 20 seconds.
  2. Then mouse over the flag image, which will make it disappear.
  3. Ask the kid what he or she sees in the white space. Is the flag red, white, and blue?

Reviewed by: Eric H. Chudler, PhD
Date reviewed: August 2011

Kids Health

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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