This newfangled LED-Lighted Newton's Cradle takes the classic desktop distraction—and subtly educational physics demonstration—to a whole new level. Instead of the traditional steel balls, this example uses plastic balls with imbedded LED lights. Just like the original, pull back a ball on one side and let it fly. The resulting impact with the stationary balls creates a compression wave that transmits the kinetic energy to the last ball at the other end, which flies up.

The physics of this can get pretty complicated, but for our purposes, it's just fun to watch the mesmerizing swinging pendulums. Thanks to the color-changing LEDs within each ball, this Newton's Cradle is as much fun to watch in the dark as in the light. Even when the spheres aren't swinging, the colorful lights flash on and off in a rainbow of colors. Takes six AA batteries (not included).