How two eyes help you better judge where objects are.

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

1. Put a cup in front of your partner. It should be about 2 feet away from him or her.
2. Ask your partner 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 your partner that you'll drop the penny whenever he or she says, "Drop it!" The idea is for your partner — with one eye closed — to judge when the penny is over the cup so the penny will drop into the cup.
5. Give your partner five tries with one eye closed, then five tries with both eyes open. Which way worked best?

Your Eyes