A discrepant event activity

1. Materials
• 5 Toothpicks
• A flat surface
• Water

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

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

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

5. Procedure
Watch as the toothpicks form a star.

6. 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.

7. Possible Student Misconceptions

8. 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?

9. 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.

10. Sources
• http://biology-forums.com/index.php?topic=572
• http://weirdsciencekids.com/ToothpickStar.htm
• http://0-ereserve.randall.uncw.edu.uncclc.coas