How to Grow a Rainbow Experiment

My kids always loved simple and colorful science activities. One of our favorites was the How to Grow a Rainbow Experiment. It doesn’t require fancy tools or a science lab. Just a few things from around the house, and a curious kid ready to explore.

If you’re looking for more hands-on learning, you’ll enjoy the list of Simple Homeschool Science Experiments. I keep it bookmarked for days when I need something easy, quick, and meaningful.

This post will walk you through a fun activity that mixes science, color, and creativity. It’s great for kids from preschool up to early elementary. And best of all, it actually works.

This post may contain affiliate links meaning I get commissions for purchases made through links in this post. Read my disclosure policy here.

Uncommon Facts About Rainbows

Rainbows are full of surprises beyond their bright colors. These lesser-known facts can make your next rainbow chat even more fun and interesting:

• You can see a circular rainbow if you’re in the right place—usually from an airplane or a mountain top
• Rainbows can appear at night, and they’re called “moonbows”
• No two people see the exact same rainbow due to differences in viewing angles

Recommended Rainbow Books

If you’re doing a rainbow activity, books can help bring the concept to life. There are numerous engaging reads that showcase rainbows in new and exciting ways.

Rain Before RainbowsHow the Crayons Saved the RainbowThe Rainbow Beeall about RAINBOW: Encyclopedia Book for kids age 5 and upRainbow: Ready-to-Read Level 1 (Weather Ready-to-Reads)Did You Know? The Rainbow Edition

 

How Science Experiments Help Kids Learn About Rainbows

When we add simple science projects into our week, my kids remember the concepts better. Here are a few ways to keep it interesting:

• Let your child guess what might happen before the experiment
• Talk about real-world rainbow sightings they’ve had
• Repeat the activity with different colors or materials
• Use books or videos to connect the experiment to a larger science topic

Recommended Earth Science Printable Packs

If you’re interested in Earth and weather topics, I have some Earth Science printable packs available in my shop. They’re fun, age-appropriate, and make science easier to understand.

What’s the science behind this rainbow activity?

This experiment works because of capillary action. Water climbs up the paper towel, bringing the colors along with it. It’s one of those things that seems like magic until you explain the science. Kids can learn:

• How water moves through materials
• Why certain markers work better than others
• What happens when colors mix naturally

Recommended Rainbow Toys

Rainbows always catch kids’ attention, especially when they can touch or build them. Toys with bright colors and sorting features are perfect for open-ended play and learning.

Sarah’s Silks Rainbow Streamer – 8′ Long Twirling Ribbon Wand for Kids | Montessori and Waldorf ToysWooden Rainbow Stacking Toy, Wood Stacker Arch Game, Montessori Arch Bridge Rainbow Building Blocks, Colorful Stacking Blocks Puzzles for Kids 2 3 4 5 Years Old, Rainbow Decor ToysRainbow Sorting SetPeaceable Kingdom Shimmery Rainbow Floor PuzzleSkillmatics Magnetic Matching Activity – The Alphabet Rainbow, Preschool Learning Toy & Game for Kids, 35+ Magnetic Pieces, Gifts for Girls & Boys Ages 3, 4, 5, 6PLUS PLUS 70 Piece Interlocking Building Blocks for Kids, Open Ended Connecting Toys, STEM Bin Classroom Mini Manipulatives – Rainbow Mix Play Tube

 

Growing a Rainbow Experiment Supplies

• paper towel
• Scissors
• water
• Large bowl
• Washable markers
• Clip with magnet

365 by Whole Foods Market, Paper Towels 75 Sheet jumbo Rolls 6 Count, 75 CountCrayola Broad Line Markers (12 Count), Washable Markers for Kids, Assorted, Back to School Essentials, Teacher Classrooms Must Have, School Supplies, 3+VNDUEEY 6 Pack Fridge Magnets Refrigerator Magnets, Magnetic Clips for Whiteboard, Magnet Clips for Kitchen Office Organizing & Decorating

 

Making the Rainbow Science Activity

I tried this activity with my daughter when she was younger, and she couldn’t stop watching the colors rise. It was a remarkably simple setup, but the way the colors climbed up the paper was truly fascinating.

We discussed how water moves and why the colors didn’t remain at the bottom. I had her draw her predictions before starting, which made it even more interactive. She was thrilled when her guesses were close.

The best part was how easy it was to clean up. I didn’t have to hover the entire time, and it was something she wanted to do again. The prep time took about 5 minutes, and the whole activity lasted around 15 minutes, including the observation time.

More Science Experiments to Try

Want more fun ideas? Here are a few more science activities to explore:

• Color Experiments For Kids
• Rainbow STEM Activities
• How to Grow a Crystal
• Ice Cream Volcano Experiment
• Balloon Air Pressure Experiment for Kids by Darcy and Brian
• Humpty Dumpty Preschool Science Activities by Homeschool Preschool

This colorful capillary action science experiment is one of those easy wins you can pull out when the day needs a bit of color and discovery. It’s a gentle way to mix learning with fun, and it never fails to grab their attention.