Theory: A tuning fork gives off a pure tone when struck. Mounted on a box (one end closed) which is resonant at the frequency of the fork amplifies the sound.
Description: These tuning forks on boxes are best used in pairs of the same frequency. Point the box openings at each other, and strike one of the forks. If you stop that fork after a few seconds, you will hear the same tone coming from the other fork, set into vibration by the first one.
Setup time: 3 minutes.
References: (available in the demo room)