Enjoy this simple experiment which turns broken sticks into an expanding star!
You will need
- Pipette or straw
- Bend 5 toothpicks in the middle, snapping them but not breaking them completely.
- Put the 5 bent toothpicks into the middle of a plate with the middle broken points all touching
- Carefully put a few drops of water into the centre of the plate using a pipette or a straw where all the points meet.
- Now wait and watch. Notice how the toothpicks begin to move into a new place to create a star.
- Try adding food colouring to the water to make a coloured star
- Can you arrange the toothpicks into a different starting arrangement to create another shape once the water has been added?
Have you ever noticed how an outside wooden gate or door becomes swollen and difficult to open after a lot of rain? The reason this happens is because wood is able to absorb water and does so by a process called capillary action, adhesion and cohesion. This is the same process that plants use to carry water against gravity from the roots of plants up to their leaves.
When dry wood begins to absorb water, the bent wood fibres begin to expand which has the effect of straightening them. As the toothpicks straighten out, they push against each other opening up into a star.