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Walking Water Experiment: A Fun and Colorful Rainbow Science Activity

Updated: Aug 15, 2023

Hey there, science enthusiasts! If you're searching for a fun, simple, and visually striking experiment to do with kids aged 5-10, the walking water experiment is a fabulous choice. Not only does it demonstrate capillary action, but it's also an excellent way to ignite a child's curiosity and set the stage for further scientific exploration. Let's dive in!

Materials Needed for Your Walking Water Experiment:

  • Clear plastic or glass cups (5 - 7)

  • Paper towels (preferably the absorbent kind)

  • Food coloring (primary colors: red, yellow, and blue)

  • Water

Step-by-Step Guide for the Walking Water Experiment

Water usually flows downward, but did you know it can also "walk" sideways between cups? The Walking Water Science Experiment is a great way to see this in action. It's easy to set up and doesn't take much time. Let's get started and discover the science behind walking water!

Set Up the Experiment:

  • Place 6 cups in a circle or in a straight line.

  • Fill every other cup about two-thirds full of water.

  • In the first cup, add a few drops of red food coloring, in the third cup, add blue, and in the fifth cup, add yellow.

Preparation of Wicks:

  • Fold a paper towel lengthwise several times to create a wick. It should be about an inch in width.

  • Make enough wicks for each gap between cups and extras to connect the end cups if you're setting them up in a line.

Walking Water:

  • Place one end of a paper towel wick in a cup with water and the other end in an empty cup next to it.

  • Do this for all the gaps. You should see the paper towels start to absorb the colored water.


  • Over the next several hours, watch as the colored water "walks" up the paper towel and down into the empty cup.

  • Eventually, the water in the two adjacent cups will level out and mix. Red and yellow will produce orange, yellow and blue will become green, and blue and red will turn purple.


  • Ask the kids or students why they think the water moved against gravity.

  • Discuss the concept of capillary action: the phenomenon where liquid flows in narrow spaces without external forces like gravity.

Further Investigations with the Walking Water Experiment:

Different Materials: Replace paper towels with other materials like cotton strings, cloth strips, or even toilet paper. How does the rate of water absorption change?

Adjust Liquid Volume: Start with different amounts of water in the initial cups. Does a fuller cup make the water walk faster?

Temperature Effects: Use warm water in one set of cups and cold water in another. Observe any differences in the rate of absorption or color blending.

Different Colors: Use other food coloring shades or even try making secondary colors initially to see what new colors you can create in the empty cups.

Different Vessels: Experiment with taller glasses or wider containers. Does the height or width of the container make a difference?

Paper Towel Length: Try longer or shorter paper towel strips. How does the length affect the speed and amount of water transfer?

Exploring Porosity: Get different brands of paper towels and discuss the idea of porosity. Which brand works best? Why might that be?

The walking water experiment isn't just visually delightful; it's a hands-on way to teach children about basic scientific concepts. It's also flexible enough to allow for plenty of additional investigations and inquiries. The real joy is in seeing kids' eyes light up as they engage with the process, ask questions, and explore further on their own! So, put on your lab coats, little scientists, and let the wonders of science sweep you away. 🌈🔍🧪


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