Radio waves, a miracle of science... and darn fun to play with too. What you can't see in this pic is the radio controlled dump truck that carries all those little balls around.
Pull the bowling ball up one chute, let it go and a tennis ball in a neighboring chute goes flying up to the ceiling, fun fun fun:-)
The dizzy machine the boys called it, and now I can't remember what the sign actually says...
This one uses air and water pressure to shoot the bottle up toward the ceiling
A funny robot.
It burps. Boy + burp= funny.
Magnets. Isn't it fun how metal sticks to metal under the influence of magnetism? :-)