Learn how to Grow a Rainbow with this EXCITING and EDUCATIONAL science experiment that demonstrates absorption and capillary action in an inviting way!
This rainbow science experiment is so COOL and EASY, especially with our simple directions, video tutorial, learning science worksheets, and tips for success. Trace and color the rainbow template and get ready to amaze your kids! Thank goodness it’s so easy to do because once you start this science experiment your kiddos will want to do it again again…at least mine did!
This science experiment is perfect for learning about Absorption and Capillary Action. It can also be done as a fun St. Patrick’s Day science activity, Weather and Rainbow Activity, or Spring Science Activity.
See all our Science Activities Here.
It’s similar to the rainbow walking water science experiment, except you cut the paper towel out into an arch shape so it looks more like a rainbow and displays the colors clearly so kids can easily observe the movement of water through the paper towel. I have a tip on how to place your paper towel so you don’t have to hold it while the rainbow is growing to make it easier to watch and eliminate some user errors.
While performing the Rainbow Paper Towel Experiment My older children (Little Dragon, age 9 and Little Tiger, age 11) concentrated on learning about capillary action (movement of water through an object).
My preschool kiddo (Little Pup, age 3) focused on absorption (liquid being absorbed). After watching the experiment he decided to draw his own rainbow. I LOVE it when activities like this inspire my children to explore and try new things.
BOOKS TO ENJOY WITH THIS ACTIVITY:
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Grow a RAINBOW Paper Towel Experiment
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- Absorbent Paper Towels (I used Bounty select-a-size and folded it in half so we could cut out two rainbows at a time.)
- Washable Markers (Red, Orange, Yellow, Green, Blue, Purple)
- Baking Dish with at least 1/2 in. of water in it
- Glass Bowl that fits upside down in the dish of water
- Optional: Learning Worksheets
Watch our Video Tutorial to see how to do this experiment. The rainbow template, directions, and learning worksheets can be purchased and downloaded.
- Take your dish and fill it with 1/2 in. of water.
- Place the glass bowl upside down inside the dish.
- Print the rainbow templates out. You may want to put them inside a plastic page protector to keep them dry and reusable.
This is a picture of the back of the experiment showing you how to place your bowl in the dish of water. At this point, do not place a paper towel on the bowl just yet.
Draw a rainbow on the paper towel with pencil. You can draw your own or kids can trace the Rainbow Cutting template provided in the science packet so they can perform the science experiment as independently as possible.
Cut out the rainbow.
TIP: You can fold the paper in half and cut out 2 rainbows at the same time.
Draw the colors of the rainbow on the bottom of the rainbow. To help children draw the colors of the rainbow in order, they can place the paper towel on the Rainbow Drawing Template included in the science packet.
Make sure to draw enough dye onto the paper towel.
Now it’s time to grow the rainbow.
Carefully dip the bottom of the paper towel rainbow into the water and place it on the side of the bowl. The water will hold it in place.
Tip: **Don’t submerge all of the color under the water because the marker will leak out, and the rainbow won’t grow as colorful.**
Watch the water climb as the paper towel absorbs the entire colored portion of the paper towel. See how far the water takes the colors.
Note: If the rainbow does not make it all the way to the top of the arch, try raising the water level or do the experiment again by drawing more color on each side of the paper towel.
Why Does the Rainbow Grow? Science Explained
Since paper towels are porous and made with tiny spaces between the fibers. As the paper towel is dipped in the water, the water adheres to the paper towel and fills the tiny spaces as it’s absorbed. As it does so, the ink pigments of the rainbow move with the water, causing the rainbow to get larger and “grow” as the water and colors travel further up the paper towel through capillary action.
Science Worksheets (Increase LEARNING with this Resource)
The printable science activity pack includes the supply list, directions, and 2 learning worksheets.
The Science Activity Pack includes 1 worksheet focused on Absorption and 1 worksheet focused on Capillary action. This means you can choose which one to use for your children or you can perform the same experiment in a multi-age classroom or homeschool as it guides them through the scientific process. Find out more: