In this easy demonstration (3rd on the page), learners explore depth perception by conducting a test with two pencils. Learners hold the ends of two pencils, one in each hand at arm's-length from their body. With one eye closed, they try to touch the points of the pencils together. They will discover this task is much easier to complete with two eyes open. This experiment can also be done with fingers, but pencils make the effect a bit more dramatic.