The Invisible Force Savage Sun Useful Illusions Students are often amazed at the effects that a simple glass of water can have on light.
Water can actually distort images in some fairly astonishing ways.
To begin this activity, ask your students to drop a penny into a clear, standard-sized beaker of water, then stare at the penny through the side of the beaker. Next, ask them to put a pen or pencil into the beaker, halfway out of the water, and then view it again from the side. The pencil will seem broken, as if the half below the water were unconnected to the half above it. When their demonstrations are complete, ask students to speculate about the reasons behind these optical illusions. Conclude by asking students to imagine three ways in which each of these water-based optical illusions could prove useful in technology.