What to Get:
- A foam tray (like the kind meat comes on) or a piece of non-corrugated cardboard
- A shallow tray, bowl, or baking sheet full of water
- Liquid dish soap
- A toothpick
- Scissors
- Pen
What to Do:
- Cut the foam tray or cardboard into a boat shape as shown below. A good size is about 2 inches long.
- Dip the toothpick into the liquid soap and use it to put a dab of soap onto the sides of the notch at the back of the boat.
- Carefully set the boat onto the surface of the water and see what happens.
The Science Behind the Experiment:
Soap is a surfactant, a substance that breaks the water’s surface tension. The movement of the water molecules separating from one another creates enough force to push a lightweight boat across the surface. If you want to repeat this experiment, you’ll have to rinse the tray thoroughly to remove any soap residue from the previous experiment.