Make a Color Reveal Growing “Worm”

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This is a great summer activity for kids who are into coloring and art. You start the activity by coloring a paper towel with markers. This was my art loving older daughter’s favorite part. My other two kids aren’t as into coloring, so they enjoyed watching the “worm” grow at the end the most. Either way, this activity has something for everyone.

This activity takes a little more time than most of the simple STEAM activities we have shared this summer, but the prep time is part of the fun! Kids are coloring, and then rolling the paper towel around the pencil or straw. It is all worth it to get the awesome color reveal as the “worms” grow before your eyes. My kids were very excited and impressed by how the color magically revealed as the worms grew.

We were inspired by a post we saw on Pintrest. We started with that activity and made it our own, and be sure to stick around for the STEAM Concepts Learned so you can understand the science behind why this works.

Watch the Activity:

I’ve made a YouTube video and Instagram reel of this activity for you to watch a full step by step video of this activity on your viewing platform of choice. Both videos are linked below.

Watch on Engineering Emily’s YouTube channel:

Watch on Engineering Emily’s Instagram page:

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Activity Overview:

This is an exciting kids activity with a focus on the A (for Arts) in STEAM. Kids will color a paper towel, then practice their fine motor skills as they roll it around a straw to make the worm. Then, they will add water to watch the worm change color and grow before their eyes! This activity is recommend for children ages 3+.

Materials:

Safety:

I recommend setting down a table cloth or place mat before beginning this activity. Markers can get messy, so this will help protect your table from accidental stay marker lines or water spills. Have extra towels on hand to clean up any water spills to prevent slips or falls.

Procedure:

Set a paper towel long ways facing the child.

Ask them to color the bottom half of the paper towel using the washable markers. The more colors and patterns the better!

Place a pencil or straw at the bottom of the paper towel.

We used a straw, but I think a firm pencil would have worked a lot better

Roll the paper towel around the pencil.

Once it’s rolled, use the glue stick to glue the top of the paper towel to the roll to keep it rolled up. This will eventually be the “worm”.

Optional: use a permanent marker to draw a face and stripes or other decorations on the outside of the worm, if desired (we did this in the Instagram video, if you want to see an example).
Hold up the roll vertically over the plate.

Scrunch the paper towel down the pencil or straw and remove from the pencil. You will be left with a small white “worm” on the plate.

Slowly pour a little water over the scrunched up paper towel (the “worm”). You can pour it on with a measuring cup, or use a dropper to add the water (which is easier and more fun for kids).

The “worm” will begin to grow and the color will be revealed.

Repeat as many times as you want!

We drew faces with permanent marker on these worms. Do this before you remove from the pencil/straw.

STEAM Concepts Learned:

Just like in our color changing flowers post from last week, this activity works due to capillary action. Capillary action is how liquid can flow in narrow spaces, often defying gravity. As we learned last week, plants absorb water from the ground through their roots and move it to their leaves using capillary action. Similarly, in this experiment the water is attracted to the fibers in the paper towels which allows it to move all around the paper towel, expanding it back to its full size.

Several other forces help make the capillary action possible. These are adhesion between water the the paper towel, and cohesion which is the attraction of water molecules to each other. All these forces combine to pull the water into the paper towel. The wet paper towel stretches back out to it’s full length, making it look like the “worm” is growing.

Meanwhile the washable markers are water soluble, making them “bleed” when wet. The washable maker colors will spread all over the wet paper towel – that’s what causes the color reveal. If you drew a face or lines on the outside of the “worm” with permanent marker, it will not be affected by the water. Permanent markers are not water soluble, so the marker will not move from where it was drawn when water is applied.

This activity is hands-on for kids for most of the activity: they color and roll the paper towels, then drop water onto the worms. But once the worms are wet, it becomes an observational activity to watch the worms grow and change color.

My kids were disappointed that they couldn’t play with the “worms”. They were expecting the “worms” to be something they could pick up and play with. But the finished “worms” are soggy paper towels with color dripping from them that will get all over hands, so it’s not something kids can really pick up and play with.

At first my kids said they didn’t love this activity because they couldn’t play with the “worms”, but then I reminded them how much fun they had until they discovered they couldn’t play with the “worms.” Eventually, they decided they did enjoy the activity after all, and we repeated it a few times.

My kids were surprised by how much the “worms” grew and how the color was magically revealed by adding the water. It was a fun summer family activity for us. We hope you try this fun, colorful, and art focused activity and let us know how it goes of you!

If you liked this activity we have a similar activity involving colors changes and capillary action! Check out my Walking Water Rainbows activity – it is seriously SO COOL!