This rainbow water experiment is such a fun activity to get kids interested in science. They’ll get to watch water travel across their paper towel bridges and create a new color in an empty cup!
Whether you’re making a fun experiment for St. Patrick’s Day, learning about new science concepts or just love rainbows, this activity is sure to get kids excited and curious, which is what science is all about!
Would you like to save this?
We'll email this post to you, so you can come back to it later!
What is the Traveling Rainbow Water Experiment?
The walking water experiment is a simple kids’ science activity around capillary action and color mixing where colored water ‘travels’ through paper towels, and the colors mix in the empty cups to create a rainbow.
Why Kids will Love this Rainbow Experiment
- When the water travels up the paper towels it feels like magic!
- Adding the color mixing makes you wait and see how the experiment will work.
- After making a rainbow, kids will have all kids of ideas to mix different colors- you can set up smaller areas to test out their theories!
- It uses everyday materials for a low-cost activity.
- You can use it to help learn the difference between primary and secondary color blending in a fun way.
Supplies for Your Rainbow Water Experiment
- 7 clear glasses (I grabbed this pack of small plastic cups to use)
- Paper towels- the select a size is easiest for this project, then you’ll fold it into thirds
- Food coloring in primary colors- the liquid kind is easiest for this experiment and I’d recommend washable.
- Water (for a fun way to extend the experiment, try it at different temperatures!)
How to Make Your Walking Water Rainbow
- Set up your glasses in a straight row, or you can try a circle.
- Pour water into every other cup. I filled them pretty full, and I do think it made the water travel a bit quicker.
- Add red food coloring to your first cup, I recommend 3 drops otherwise it can easily overpower the yellow. Add 4-5 drops of yellow food coloring to your third cup, then 4-5 drops of blue to your fifth cup and add 3-4 drops of red to the final cup. If you’re doing a circle you won’t need the last cup of red water.
- TIP: use less red drops in the first cup because it will mix with yellow in the empty cup to make orange, and the red could start to overwhelm the yellow.
- Fold your paper towels into thirds, making a strip shape. Dip it into one cup, then fold over, making an arch, into the cup next to it. Repeat until there is an arch over each cup.
- Grab your camera! It’s fun to document the process as the water travels between each cup!
FAQ
Frequently Asked Questions
How long does this walking water experiment take?
It depends on your water temp, how far apart the glasses are, and how thick the paper towel is. Ours took about an hour. You could experiment with variables to try to speed it up.
What are the best paper towels for this experiment?
The ‘select-a-size’ thicker paper towels seem to work best. We folded ours into thirds.
How many cups or jars do you need to make a walking rainbow?
At least 6, 7 if you are doing a straight line as we did.
Tips and Variations to Try
- If you want the rainbow to travel faster, try using warmer water. When we did this experiment it took about 45 minutes to an hour, but it was a warm humid day and we used room temperature water.
- When trying to see if we could make it travel faster we added a few drops of water on the arch of the paper towel too.
- If the colors aren’t mixing well, adjust how much food coloring you’re using or how far apart the cups or jars are.
- Thicker paper towels seemed to work better.
Rainbow-Themed Books that Pair well with this Activity
- Planting a Rainbow, by Lois Ehlert
- Bear Sees Colors by Karma Wilson and Jane Chapman
- Rainbow Stew by Cathryn Falwell
Looking for more science experiments and rainbow activities for kids?
- How to Make Cloud Dough
- How to Make Oobleck
- Rainbow Template- Free Printable Coloring Page
- Froot Loops Rainbow Craft
- Fluffy Cloud Slime
Get creative ideas for recipes, crafts, decor, and more in your inbox!
Get the How-To
Supplies
- 6-7 clear cups or jars
- 3 cups water- enough to fill your clear cups or jars most of the way.
- 7 paper towels, folded into thirds (select a size or torn into half.)
- 3-5 drops food coloring in primary colors- red, yellow and blue
Instructions
- Set up your glasses in a straight row, or you can try a circle.
- Pour water into every other cup. I filled them pretty full, and I do think it made the water travel a bit quicker.
- Add red food coloring to your first cup, I recommend 3 drops otherwise it can easily overpower the yellow.
- Add 4-5 drops of yellow food coloring to your third cup.
- Add 4-5 drops of blue to your fifth cup.
- Finally, add 3-4 drops of red to the final cup. If you're doing a circle you won't need the last cup of red water. TIP: use less red drops in the first cup because it will mix with yellow in the empty cup to make orange, and the red could start to overwhelm the yellow.
- Fold your paper towels into thirds, making a strip shape.
- Dip it into one cup, then fold over, making an arch, into the cup next to it.
- Repeat until there is an arch over each cup.Grab your camera! It's fun to document the process as the water travels between each cup!