This is interesting, esp. as schools are cutting down recess/playtime/phys ed to nothing, and the nutritional value of the food kids eat in schools is completely inadequate. Brains can't work well if the rest of the body isn't being taken care of.
10 cool demos with tuning forks: determine the speed of sound...transfer sounds using a laser beam...bounce a ping pong ball without touching it. Many for high school, and some cool things for middle school intro to waves and sound.