• 1 white basket-style coffee filter

• Paperclip

• Water

• Clear plastic cup

• Ruler

• Black felt tip pen or marker (nonpermanent)

1. Fold coffee filter in half three times to form a triangle. Use a paper clip to hold it together, if necessary.
2. Make a ¼ inch dot with the black marker about a ½ inch above the point of the triangle. Allow the black dot to dry.
3. Put ½ inch of water in the bottom of the cup.
4. Place the tip of the coffee filter in the cup, making sure the dot does not enter the water.
5. Watch what happens as the filter absorbs the water.
6. What did you discover about the color black?
7. Experiment with other marker colors.

Want to Learn More? Read an article related to this activity:

• Color and Light

• Sources of Light

• The Composition of Color

To find this experiment and many more please download the Lighten Up! Discovering the Science of Light book, developed through a partnership with the Optical Society of America’s Foundation (OSAF) and the Girl Scouts of the USA.