Make a Rainbow at Home in 4 Steps

Materials you'll need

• 2 glasses or cups of water
• 1 paper towel
• Washable markers in rainbow colors: red, orange, yellow, green, blue, purple

 

Step-by-step tutorial

Step 1: Fold a paper towel in half lengthwise and cut to create a long strip.

Step 2: Using your washable markers, color thick rainbow stripes (red, orange, yellow, green, blue, and purple) across each end of the strip. Leave the middle section white and uncolored.

Step 3: Fill two glasses with water. Drape the paper towel between them so each rainbow-colored end hangs down into a separate glass.

Step 4: Watch and wait! Water will slowly climb up through the paper towel, carrying the marker colors with it. As the two rainbow ends meet in the middle, the colors blend together into a full rainbow bridge.

Learn more

This experiment works thanks to capillary action — water's amazing ability to travel through tiny spaces without any help from gravity. Paper towels are made of plant fibers called cellulose, and there are microscopic gaps between those fibers. Water molecules are attracted to the cellulose and creep upward through those gaps, carrying the marker pigments along for the ride. It's the same science that helps trees pull water all the way from their roots up to their very highest leaves!