✅ What you'll learn
- The science concept behind the experiment
- How to set it up safely
- What to observe and record
- Why the result happens
💡 Perfect if you're thinking...
Walking Water is one of the most beautiful experiments to watch — coloured water literally 'walks' from one glass to another along a paper towel bridge, and the colours mix in the middle to make new colours! It teaches kids about capillary action and how plants drink water.
🧪 What You Need
- 6 clear glasses or cups
- Water
- Food colouring — red, yellow, and blue (the three primary colours)
- 6 paper towels (folded into long strips)
How to Set Up Walking Water Step by Step
- Line up 6 glasses in a row — close enough together that a folded paper towel can stretch between them.
- Fill alternate glasses with water — glasses 1, 3, and 5 get water (about three-quarters full); leave glasses 2, 4, and 6 empty.
- Add the primary colours — put RED in glass 1, YELLOW in glass 3, BLUE in glass 5. Stir well.
- Fold the paper towels — fold each into a long strip about 3cm wide.
- Bridge the glasses — bend each paper towel into a U-shape and put one end in a coloured glass and the other end in the next (empty) glass.
- Predict what will happen — what do you think will happen in the empty glasses?
- Wait and watch — within minutes, water will start climbing up the paper towels.
- Come back in 30-60 minutes — the coloured water 'walks' along the paper towels into the empty glasses, and the colours mix to make ORANGE (red+yellow), GREEN (yellow+blue), and PURPLE (red+blue)!
🔬 What's Happening? (The Science)
This experiment shows capillary action — the amazing ability of water to climb up tiny gaps against gravity. Paper towels are made of plant fibres (cellulose) full of microscopic spaces. Water sticks strongly to itself (cohesion) AND to the paper fibres (adhesion). These two forces work together to pull the water up through the tiny spaces in the paper, against gravity, into the next glass. This is exactly how real plants drink — tiny tubes inside their stems use capillary action to pull water up from the roots all the way to the leaves, even on tall trees! The colours mix because each empty glass receives water from both neighbouring coloured glasses.
🌟 Did You Know?
Capillary action is so powerful it can pull water up the world's tallest trees — the giant redwoods of California, which can be over 100 metres tall! Scientists are still amazed that trees can lift water that high using only this 'wicking' force in their tiny internal tubes. The same physics that walks colour from one glass to another keeps a 100-metre tree alive.
🎯 Try This: Experiment Variations
- Try only TWO glasses — does it still work? How fast?
- Use different paper (printer paper, kitchen roll, tissue) — which works best?
- Try thicker vs thinner paper towel strips — does width matter?
- Time how long it takes for the colours to fully mix and record your results.
📚 Sources & Further Reading
Written by Parikshet More (KidsFunLearnClub, Dubai) and reviewed for accuracy. Facts checked against the references above.
🧠 Quick Quiz — Test What You Learned!
Created by Parikshet & Dad
Hi! I'm Parikshet, an 11-year-old creator from Dubai who loves drawing, art, science experiments, and golf. My dad and I run KidsFunLearnClub to share fun learning activities with kids around the world. We've created over 1,900 tutorials and videos to help you learn and have fun!
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Explore AI for Kids → What is AI? Start hereFrequently Asked Questions
What is capillary action?
Capillary action is the way water can climb up tiny gaps and spaces against gravity. It happens because water molecules stick strongly to each other AND to the surface they're touching (like paper fibres). Together, these forces pull water up through the tiny spaces — which is why paper towels soak up spills, why oil rises in a wick, and how trees drink water through their stems.
How do plants drink water?
Plants drink water through their roots and pull it all the way up to their leaves using exactly the same capillary action as in this experiment! Inside their stems are tiny tubes called xylem, full of microscopic spaces. Water clings to itself and to the tube walls, and is pulled up by capillary action plus evaporation from the leaves at the top. This lets even 100-metre-tall trees drink water from their roots.
Why do the colours mix in the empty glasses?
Each empty glass sits between two coloured glasses, and the paper towels pull water from BOTH sides into the empty glass at the same time. The two colours blend in the middle: red + yellow = orange, yellow + blue = green, and red + blue = purple. This is also a great chance to learn how primary colours (red, yellow, blue) mix to make secondary colours.
How tall can capillary action lift water?
Astonishingly tall! The giant redwood trees of California — among the tallest trees on Earth — use capillary action (plus evaporation from their leaves) to lift water over 100 metres from their roots to their topmost leaves. Scientists are still studying exactly how trees do this, because it pushes the limits of what's physically possible. The same forces in your experiment power those giant trees.