Grow a rainbow with your kids! This simple experiment is so easy and fun! You just need markers, a paper towel and two cups of water! This experiment is quick to setup and just takes a few minutes to finish!
The great thing about this experiment is young kids can do almost all of it on their own! Our kids completed it several times! As always, make sure you supervise the kids and be sure to ask questions about the science experiment!
Grow a Rainbow Science Experiment
- Two Clear Cups
- Marker (Washable Markers)
- Paper Towel
Video of Grow a Rainbow Experiment
Grow a Rainbow Instructions
- Take a paper towel and fold it in half so it absorbs the water better.
- You will then want your kids to measure the paper towel and cut it at around 7 inches. You don’t want it too long, as the colors might not connect in the middle if it is.
Our cups were so short that the paper towel could have been a bit shorter and the colors would have met in the middle even better.
- You will want to use the markers to fill in about 6 or 7 rectangles on both sides of the paper towel. They should extend out about an inch and a half. Use the colors of the rainbow or close to it: Red, orange, yellow, green, blue, indigo, violet.
- After that, pour water into the 2 cups. You will want the cups to be about 1/2 to 3/4 full. This will depend on how tall your cups are.
- You will now gently put one end of the paper towel in one cup and the other end in the second cup – making a bridge between the two cups. Try to make sure the paper towel doesn’t fall too far into the water. If it does pull it out slightly or separate the cups a little more.
- Now you just wait and watch the fun! The colors should connect in 5 – 10 minutes!
- Do not place the paper towels too far into the water as the color will dissolve into the water and not travel as high.
- The more marker dye you use, the easier it will be for the colors to travel up and meet.
- Make sure you use a really washable marker. The more washable they are, the better the colors will travel up the napkins.
- Use an absorbent paper towel.
The kids had a blast with this science activity! They enjoyed trying different colors and amounts of marker. They would try to color in the sides of the paper towel with extra marker dye to make the colors connect even faster.
This activity definitely kept them busy and having fun. And it was easy to set up and quick to clean up too!
How does this simple science activity work?
In this rainbow experiment, capillary action is the reason the water moves up the paper towels.
Capillary action occurs because water is sticky since water molecules like to stay together (cohesion). And thanks to adhesion, water sticks to other substances and will move along their walls. This allows the water to move up the paper towels!
This same action is how water moves up into plants from the roots! It’s also why paper towels and pool towels are great at absorbing water!
Extend the Fun
Your kids can extend the fun by trying different colors, different paper towel lengths and different amounts of marker. Our kids tried to use a lot of marker to get the colors to grow faster!
They absolutely loved this science experiment! It was one of the easiest we have tried and they had a blast trying lots of variations!
Using markers, water and paper towels is a great way to show capillary action at work and amaze your kids!
Check out the Rainbow Walking Water and Color Changing Flower experiments below for more fun experiments showing capillary action.
More Fun Rainbow Science Experiments
The rainbow walking water is our most popular science activity! This one uses capillary action too!
You can use the colors of the rainbow with this color changing flower experiment! This is another experiment using capillary action.
This rainbow skittles experiment is a fun rainbow activity for the kids!
Looking for more capillary experiments. This Celery Food Coloring Experiment is fantastic! – via Little Bins for Little Hands