Appropriate grades or age groups:
Elementary or Middle School

Estimated time to complete this project:
1 hour

Materials:
5 ft board, cardboard, paint, string, 2 matchbox cars (identical)

Instructions:
Paint the board...(we chose green).
After the paint dries, mark off 1 ft, 3 ft, 5 ft increments.
Attach two pieces of string to the board (lengthwise) with the cars attached to each string.
Put the cardboard piece at the end of the board and cut a square in it to look through.
Close one eye and try to line up the cars, pulling on the strings at 5 ft away, 3 ft away and then 1 ft away. Then open both eyes and try to line the cars up side by side at 5 ft away, 3 ft away, and 1 ft away.
Measure each time how many centimeters or inches the cars are away from each other. Our hypothesis was that when you have both eyes open your depth perception is more accurate and the cars will be lined up closer.

Other comments or suggestions:
My son was in 5th grade (last year) when we did this experiment. He placed first in his school and went on to the city regionals with this experiment. It was alot of fun.