Toothpick Star

Can you make toothpicks bend into the shape of a star?

Australian Curriculum links

• Science > Chemical Sciences > Year 6 > ACSSU095

You’ll need

• 5 toothpicks
• Pipette
• Small plate
• Water coloured with food dye

Time required

5 minutes

Try this

Snap all 5 toothpicks half way along their length so that they are bent into a V, but not completely separated – they need to be still connected.

Arrange the bent toothpicks as in the picture, without letting the ends touch.

Using the pipette 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. You may need to add a couple more drops of water.

What’s happening?

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