Toothpick Torpedo

Dab a little shampoo on the blunt end of a wooden toothpick.

Drop the toothpick in a pan of water. The toothpick will start moving in the direction of the sharp end.

How Does It Work?

Shampoo contains agents that reduce the surface tension of liquids. As the shampoo on the end of the toothpick dissolves, it reduces the water’s surface tension around it, thus releasing the water’s hold on that end of the toothpick. The water around the other end of the toothpick still has surface tension, so it pulls the toothpick in that direction.