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General Chemistry Science Fair Project

Walking Rainbow Experiment

Walking Rainbow Experiment | Science Fair Projects | STEM Projects
Get ready to witness a rainbow magically appear as colored water defies gravity and moves from cup to cup, showcasing the sticky qualities of water - the power of capillary action.


The hypothesis is that the colored water will travel along the paper towels, reaching the empty cups where color mixing occurs, ultimately resulting in a mesmerizing walking rainbow effect.

Method & Materials

You will set up seven cups in a row, fill the first with red colored water, the third with yellow colored water, the fifth with blue colored water and the seventh with red colored water. The second, fourth and sixth cups don’t have any water. Place a piece of paper towel between each pair of cups with one end of the paper towel on the bottom of each cup, and watch as a rainbow forms in the cups.
You will need clear cups, paper towels, red, yellow, and blue food coloring, and water.


The colored water climbs up the paper towels due to capillary action. When the colored water reaches the empty cups, the two different colors mix, forming a new color! All together, a rainbow is formed from the colored water moving to the empty cups and mixing to form new colors.

Why do this project?

This science project is fascinating because it demonstrates how water can move against gravity through capillary action and also see colors mixing in a visually stunning way.

Also Consider

For variations, you can try using different temperatures of water to see how it affects the speed of absorption, or you can experiment with uneven amounts of water to observe how it impacts the formation of the rainbow.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related videos

Hey there! Here are some awesome videos about this science project that we think you'll really like. They're not only super fun, but they'll also help you learn more about the science behind the project. So sit back, relax, and get ready to have some fun!!
In this demonstration from the Aberdeen Science Centre, glass jars are used in the rainbow walking water experiment, and at the end, all the jars are filled with the colors of the rainbow! The capillary action you see in this rainbow water experiment is also what draws water up through plant roots into the leaves and flowers!
Follow along with these step-by-step instructions for the Rainbow Walking Water science experiment, brought to you by the Miami Children's Museum!
This is a sped up video of the rainbow walking water science experiment from the Science Museum Oklahoma. Notice what happens to the empty glass!
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