We love simple science experiments. And this one is really easy to set-up and the kids are always amazed at the end result. Learn about color mixing and capillary action in this easy walking water experiment!

RELATED: Grow a Rainbow Experiment 

Walking Water Science Experiment

Walking Water Science Experiment

 

Here is what you will need for this activity:  

  • Paper Towel – 6 folded half sheets
  • Food Coloring – we like the liquid gel food coloring (you just need 1 drop) but regular food coloring works too
  • Water
  • 7 Small Clear Cups or Glasses
Walking Water Experiment for Kids

What is the Science Behind This Experiment?

This science experiment is a great example of coloring mixing and capillary action.

Kids can learn about how secondary colors are formed when the orange, green and purple colors are made in the empty cups.

Capillary action is what makes the dye move up the paper towel.  The water moves upward through the paper towel, lifting the food dye molecules with it. This same phenomenon is what allows trees to get water from the ground with their roots. Paper towels are made from fibers found in plants, called cellulose.

Walking Water Experiment Science

Watch the Full Video Tutorial Here

Walking Water Experiment Step-By-Step Process

1. Start by filling up 4 clear cups with water. Fill the water to almost the top of the cup.

The more water there is, the faster the walking water will travel.

Fill Cups with Water

2. Add 1 drop of red food coloring to two of the cups, 1 drop of blue food coloring to one of the cups and 1 drop of yellow to one of the cups. If using regular food coloring you may need to add a few drops.

Add Food Coloring to Cups

For the red and blue, make sure this is not too concentrated. Once the colors mix, if they are too concentrated then the purple will look more black than purple.

3. Place the cups in a line starting with red on each end. Line them up like this:
1. Red
2. Empty Cup
3. Yellow Cup
4. Empty Cup
5. Blue Cup
6. Empty Cup
7. Red Cup

Line Up Cups for Walking Rainbow Line up Cups to Make Rainbow

When the colors mix then the order of the rainbow will show this way.

4. Fold over 6 pieces of paper towel (half sheets) and trim about 1/4 off the end so they are not too long.

5. Place a paper towel into each cup and connect with the empty cups.

Place Paper Towel into Cups

6. The water and dye will immediately start to move up the paper towel into the empty cups.

Blue and red will mix to make purple.

Blue and yellow will mix to make green.

And red and yellow will mix to make orange.

Blue and Red Color Mixing Yellow and Blue Mix to Green

7. Wait 2-3 hours for the empty cups to fill with the new color that is mixed from the other 2 cups.

Now your walking rainbow is complete! You can now see each color from the rainbow in the cups and your empty cups have now been filled with the secondary colors – orange, green and purple!

Walking Rainbow Science Experiment

Note – if you would like to do the experiment in a circle instead of a straight line to save space, just make 1 red cup and place the cups in a circle (as shown in the first image).

Kids will love watching the water travel and seeing the new colors being made in this easy science experiment!

More Science Experiments for Kids

Try this fun and easy Grow a Rainbow Experiment. You only need washable markers and paper towel!

Growing Rainbow Experiment

For another fun experiment, make some oobleck! 

How to Make Oobleck

Try a rainbow rain cloud in the jar experiment!

Rain Cloud in a Jar Rainbow