Wood is hygroscopic, which means it attracts water. When wood fills with water, the wood swells. You can use this physical chararacteric of wood to perform what appears to be magic, but instead ===it is fun science!
Discover For Yourself
1. Bend five round wooden toothpicks into a V shape without breaking them apart.
2. Place the bent toothpicks on a sheet of wax paper in a star burst pattern as shown in the diagram. Put the bent parts as close together as possible in the center.
3. Fill an eyedropper with water. Place four drops of water in the opening in the center of the star burst. You want the water to touch the bent parts of each toothpick. FYI: You can wet your finger with water and let the drops fall in the center of the star burst.
4. Watch and wait until all movement stops.
The broken ends of the toothpicks absorb water and expand. This increase in size causes the angle between the ends of each toothpick to increase. The first pattern that takes shape is a five-pointed figure similar in appearance to a starfish.
The angles continue to enlarge until all motion ceases, and a fully developed five-pointed star is created.