Rainbow Walking Water Experiment


  • half sheets of papertowls
  • plastic cups
  • food dye
  • water

Pre-Activity Discussion:

What do you think the water will do? How can the water move against gravity? Ask the students what colors they think will be made when mixing primary colors. (Ex. If we mix red and yellow what will that make?)


  1. To begin this experiment, line up 2 cups and fill each halfway with water
  2. Add a different color food dye to each cup, about 5 drops. We started with blue and yellow to make green
  3. Next, fold the halved paper towel in half again and drape the ends in each cup
  4. Now, the water, along with the food dye, will travel up the paper towel and mix at the top and make green.
  5. You make this experiment bigger by adding cups and using all the colors

*Note: This may take up to an hour so be patient. You can always add more food dye if it seems to be taking too long

Post-activity Discussion:

The water moves up the paper towels through a process called capillary action. The fibers that make up the paper towels allow water to travel through the gaps in the fibers. These act like capillary tubes and pull the water up against the gravity. This is the same thing that happens in the roots of a tree


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