Seeing Sounds

If you've never seen this demonstration, it's incredible.

This is called a Chladni Plate. Originally, a man named John Tyndall found that the different frequencies at different pitches caused different patterns of sand to emerged. His patterns (seen HERE) look much different than the video because he used a bow against the side of a plate and created nodes with his fingers. Modern Chladni plates work due to a motor attached at the middle of the plate (the node) and a speaker that plays the different pitches.

For directions on how to make a Chladni Plate, google "How To Build A Chladni Plate". There are many great resources!