Walking Water Rainbow: A Colourful Science Adventure for Kids
Why Try the Walking Water Rainbow Activity?
Ever wondered how water can seem to “walk” across cups? This fascinating experiment uses capillary action to create a magical walking rainbow—right before your kids’ eyes! It’s simple, hands-on, and teaches core science concepts through vibrant, visual fun.
Whether you’re homeschooling, teaching in a classroom, or just looking for a rainy day activity, this experiment checks all the boxes: it’s educational, mess-free, and full of wow moments.
What Is Capillary Action?
Capillary action is how water moves through narrow spaces without relying on gravity—think of how plants pull water from roots to leaves. In this experiment, paper towels act like plant stems, drawing coloured water upward and across empty cups.
As the water travels, it mixes and forms new colours—making this both a science and art activity in one!
What You’ll Need
- 6 clear plastic or glass cups
- Paper towels (about 5 pieces, folded lengthwise)
- Primary food colouring: red, yellow, and blue
- Water
- A flat surface
- Optional: marker labels for cups
Pro Tip: Use absorbent paper towels for faster results!
Step-by-Step Instructions
Step 1: Arrange the Cups
Line up the six cups in a row. Fill cups 1, 3, and 5 with water (about halfway). Leave cups 2, 4, and 6 empty.
Step 2: Add Food Colouring
- Cup 1: Add red food colouring
- Cup 3: Add yellow
- Cup 5: Add blue
Stir gently to dissolve the colours.
Step 3: Fold the Paper Towels
Take 5 paper towels and fold them lengthwise into strips. Bend each strip into an arch and place one end in a full cup and the other in the adjacent empty cup.
Arrangement example:
Red → Empty → Yellow → Empty → Blue → Empty
Step 4: Observe the Magic
Wait and watch! Within 15–30 minutes, you’ll notice the colours begin to “walk” into the empty cups. Over time, new colours (orange, green, purple) will appear as the primary colours mix!
What Kids Learn
- Science Concept: Capillary action and colour mixing
- Visual Learning: Seeing primary colours create secondary ones
- Fine Motor Skills: Folding paper towels and handling materials
- Patience & Observation: Watching gradual change over time
This experiment links beautifully to nature-based learning too—how trees and flowers get their water!
Quick Variant
Short on time or supplies? Try it with just 3 cups:
- Cup 1: Red water
- Cup 2: Empty
- Cup 3: Blue water
Use 2 paper towel strips. Over time, purple will appear in the middle cup!
Downloadable Resources
- Printable Step-by-Step Instruction Sheet
- Capillary Action Science Facts PDF
- “Mix It Up!” Colour Wheel Chart
- Certificate of Completion for Young Scientists
Download the Walking Water Rainbow Activity Kit – FREE
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Parent & Teacher Feedback
“My students were mesmerised watching the colours move on their own. The science lesson just clicked!” – Grade 2 Teacher, Canada
“Perfect mix of art and science. Even my 5-year-old stayed engaged the whole time.” – Parent, New Zealand
Explore More Hands-On Science Fun
- Floating & Sinking Experiment Kit
- pH Indicator Balloon Activity
- DIY Tornado Tube: Spinning Science for Kids
- Watch It Bloom: Capillary Action with Paper Flowers
Final Thoughts
The Walking Water Rainbow is more than just a pretty experiment—it’s a visual entry point into scientific thinking. Kids learn by doing, seeing, and questioning. That’s how curiosity blooms!
Whether you’re exploring colour theory, plant biology, or just having some weekend fun, this activity guarantees bright smiles and big learning moments.
