A few weeks ago I shared our Walking Water Rainbows STEAM Activity on Instagram! This is one of the coolest, most colorful and instantly gratifying activities we have done during our weeks at home. I think other parents agree with me, because it has also been the most popular post I have shared on Instagram over the last 3 weeks.

It was so easy to set up, it worked very quickly and my kids LOVED it! In this post I’ll explain how you can do this fun activity at home with your kids too!


  • 6 clear cups or small bowls
  • Water
  • Red, Yellow and Blue food coloring
  • Paper towels


  1. Place the 6 cups or bowls in a tight circle, they should all be touching each other
  2. Fill every other bowl or cup all the way to the top with water (3 total will have water)
  3. Add 5 to 10 drops (more or less depending on the size of your cups) of food coloring to the cups with water. Put Red in one, Yellow in the next, and Blue in the third (make sure you use the same number of drops of food coloring of each color)
Step 1
Step 2
Step 3

4. Use 5 half sheet of paper towels. Fold them in half long ways (think hot dog), then in half again
* If you’re using small bowls, like ours you’ll need to cut the paper towels in half to make them shorter
5. Place paper towels connecting all the cups – one end will be in water and the other end will be in an empty cup.
6. Sit back and observe the water walk up the paper towel and move from the full cups to begin to fill the empty cups

Step 4
Step 5
Step 6

We did this activity using both large pint glasses and small custard cups. As you might guess, the experiment worked almost instantaneously in the small custard cups. Within less than five minutes the empty bowls were filled with colored water and the colors had mixed to the secondary colors. My kids helped the coloring mixing by stirring the bowls with the secondary colors.

Meanwhile, the experiment took hours instead of minutes to complete in the pint glasses. It was fun to do both ways, because we got to see one complete instantly before our very eyes, but it was also fun to keep coming back to check on the pint glasses evert 15 minutes or so throughout the morning.


  • General: Hypothesis, Procedure, Observation, and Results – before you begin ask your kids what they think will happen in the empty bowl when you add paper towels. Continue to ask questions as you are observing the capillary action, like what color is being created when blue and yellow combine? Then once it’s done review what happened and discuss the results.
  • Science: Capillary action, as defined by Wikipedia,  is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. Plants absorb water from the ground through their roots and move it to their leaves using capillary action. Similarly, in this experiment the water is attracted to the fibers in the paper towels which allows it to move up the paper towel against gravity.
  • Art: Colors – we start with the three primary colors: red, yellow and blue, and then two primary colors mix in the empty bowls to make the three secondary colors: green, orange, and purple.

This is a mesmerizing activity that you can do with materials you probably already have at home. I hope you try this with your kids and let me know how it goes!


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