Toothpicks are made of dry wood.
Using the absorbing property of wood and the surface tension property of water, you can create a fun trick to impress your kids (or friends).
In this simple experiment, we will turn broken toothpicks into an expanding star.
Before you start, be sure to watch the video below.
The second part of the video has been sped up 4x times
So don’t be discouraged if your star doesn’t expand as fast as mine.
If you are getting new toothpicks for this experiment, try to look for the multi-color pack to make a colorful star!
- 5 wooden toothpicks
- a dropper or a drinking straw
- adult supervision
- Bend the 5 toothpicks in the middle but do not break them completely.
- Put the 5 broken toothpicks in a circle with the broken points touching one another.
- Carefully put a few drops of water in the middle using a dropper or a straw.
- Now wait and watch how the toothpicks glide into place to form a star!
Video: The second part of the video has been sped up 4x times. So don’t be discouraged if your star doesn’t expand as fast as mine.
When dry wood absorbs water, the bent wood fibres expand and unbend. As the toothpicks straighten out, they push against one another opening up the inside of the star.
But how does wood absorb water?
Wood absorbs water by capillary action, adhesion and cohesion.
These are the same factors that allow plants to carry water from the roots upwards through vein-like tubes to the leaves.
Want to see more about how wood and plants absorb water? Try this awesome Color Changing Flowers experiment!
Want more water science experiment?
Water science is so much fun.
Here are tons of interesting water experiments you can do in the sink or in the tub.
4M Clean Water Science
The 101 Coolest Simple Science Experiments
Awesome Science Experiments for Kids