The toothpick star

Materials

• 5 Toothpicks

• A flat surface

• Water

Procedure

1. Break each toothpick in half, leaving the halves partially attached.

Procedure

2. Arrange the toothpicks with the broken ends as close together as possible.

Procedure

3. Place a drop of water in the enter of the toothpick configuration.

Procedure

Watch as the toothpicks form a star.

The Science Behind It

Breaking the toothpicks caused the wood fragments inside to compress. When water is added, capillary action (the phenomenon of a liquid rising in a narrow space, causing the liquid to flow against the force of gravity) causes the water to be absorbed into the toothpicks.

It is similar to when cut flowers become limp if not placed in water. Capillary action and osmotic pressure are the forces that bring water from a plant’s roots up to it’s top.

Possible Student Misconceptions

Questions to Help Students Understand

• What happens to the water as it is forced into the wood fibers?

• What are toothpicks made of?

• How can this be compared to roots collecting water for plants?

• Where else in science do we hear the word capillary?

Safety Concerns in the Classroom

• Remind students not to eat or drink anything during the experiment.

• It is possible that the toothpicks will splinter if care is not taken when handling them.

Sources

• http://biology-forums.com/index.php?topic=5728.0

• http://weirdsciencekids.com/ToothpickStar.html

• http://0-ereserve.randall.uncw.edu.uncclc.coast.uncwil.edu/eres/coursepage.aspx?cid=1990&page=docs#