Toothpick Star Trick

This fun experiment only needs a few items to enable children to enjoy creating a star.

Author: S Jones

To create this star experiment, first you will need to take the 5 new, dry toothpicks and bend them in the middle. Bend them just enough that they crack but do not completely break.
Place the toothpicks on the centre of a plate with the broken middles bits touching in the middle, making a closed, five-pointed star.
Mix a drop or two of food colouring with a little water. Use the dropper or pipette to carefully drop a couple of drops of coloured water into the middle of the star, where the star splits are the closest. You will need to add enough water for the broken ends of the toothpicks to get soaked, but you do not want to so much that the toothpicks float.
How does it work?
Toothpicks are usually made of dried wood and when you bend them, the wood fibres inside are compressed. When the water is added, the dry wood fibres absorb the water which causes the fibres to swell and expand. As these fibres expand, the toothpicks straighten themselves out, causing the ends to push against each other, which in turns opens the star.

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Extra Learning

Try with different temperatures of water to see if that makes a difference
Try adding things like sugar or salt to the water and see what happens
Use different surfaces and see if that effects the opening of the star
Experiment with different liquids - fizzy drinks, hot chocolate or coffee, milk, vinegar.