I'm going to make you a star!

Expanding Toothpicks

Materials:

· 5 toothpicks
· eyedropper
· small plate
· water

Time required:

5 Minutes



What to do:

Snap all 5 toothpicks so they are bent, but not completely in two parts - they need to be still connected.
Arrange the bent toothpicks in the centre without letting the ends touch.
Using the eyedropper add 5 drops of water to the centre of the toothpicks. Make sure the drops of water touch the bent corners of all toothpicks.

Watch the toothpicks. If necessary add a couple more drops of water.

What’s Happening?

The broken wood of the toothpicks absorbs the water they are sitting in. As the water is drawn into the toothpick (by capillary action) the wood expands. The expanding wood on the inside of the break pushes against itself which makes the toothpick straighten out. As the toothpicks push out they form the star shape.