The next day, Silver took the circuit to the summer camp where he taught and showed the campers how it worked. When it came in contact with conductive objects, they acted as extensions of the device: Users could touch the object to create different sounds, like pressing the keys on a keyboard. Silver's campers tested it out, making music with everything from apples to bicycles. Later, a co-worker suggested that Silver hook up the circuit to a pencil, since electricity can pass through its graphite core. The result was Drawdio, a pencil that plays "music" when you draw.