Walking Water Rainbow

This activity is used to teach how the color wheel works. The primary colors are red, yellow and blue. Primary colors cannot be made by other colors, but primary colors can make secondary colors, which include purple, green, and orange. This experiment is fun and super easy. Follow the directions and watch your rainbow walk.

Supplies Needed

  • 7 plastic cups or mason jars

  • 6 paper towel sheets

  • Food coloring in red, yellow, and blue colors

  • Water


  • First, take one sheet of paper towel, fold it in half and then half again. Make 6 all together.

  • Next, set out seven cups in a circle.

  • Fill 4 cups with water almost all the way full. Add one drop of red food coloring to 2 cups. Add 1 drop of blue food coloring to 1 cup and repeat with the yellow coloring.

  • Next, line the cups in this order:
    1. Red cup
    2. Empty cup
    3. Yellow cup
    4. Empty cup
    5. Blue cup
    6. Empty cup
    7. Red cup

  • Finally, place a folded paper towel in each cup, so they connect one cup to the next, and watch the magic happen.

Why It Works

  • As explained so well by The Best Ideas For Kids:

    “This science experiment is a great example of coloring mixing and capillary action. Kids can learn about how secondary colors are formed when the orange, green and purple colors are made in the empty cups.

    Capillary action is what makes the dye move up the paper towel.  The water moves upward through the paper towel, lifting the food dye molecules with it. This same phenomenon is what allows trees to get water from the ground with their roots. Paper towels are made from fibers found in plants, called cellulose.”