Make water walk
You will connect cups with folded paper and watch water enter a dry cup. The movement is slow, so a first glance can miss the change starting inside the paper.
- Science
- Explorer
- About 15 minutes
Grown-up needed: yes for setup, nearby supervision and handling water or small items
The film mentions food colouring. This page uses plain water, so follow the page.
What you need
- Three plastic cups
- Water
- Kitchen paper
- A tray
- A grown-up
The rule
Hands off once it starts.
How to do it
- Ask a grown-up to place three cups together on a tray.
- Fill each outer cup halfway with plain water.
- Fold two pieces of kitchen paper into wide strips.
- Put each strip between an outer cup and the dry middle cup.
- Leave the cups untouched while watching the paper darken.
- Check the middle cup after thirty minutes without moving the bridges.
Why it works
Water can move through the small connected gaps in paper. Attraction to the fibres and between water molecules helps wet the next part, a process called capillary action. Gravity also affects where water collects after it crosses a high point. This is not a full model of how plants move water, which includes their tissues and evaporation from leaves. Paper thickness and cup height can change the pace, so allow extra time before deciding nothing happened.
Make it harder
- Compare a wider paper strip in a separate attempt.
- Try another household paper type.
- Explain what changes if the middle cup begins at a different height.
Ask Taz
- Why does water climb inside the paper?
- Why does a thicker strip change the waiting time?
- Why is this only part of the story of plants moving water?
For grown-ups
The listed time is setup and observation time; the water may take longer to arrive. Use plain water and keep cups away from electrical equipment. A grown-up stays nearby and clears spills. Ask at dinner: “Did the paper change before the cup filled, and what did that tell you?”
Taz is an AI and can be wrong, so stay close by. Read how safety works on Taz.
Show us yours
Film your hands and what you made, not your face or name. Ask a grown-up before posting anywhere else.
Questions parents ask
Can we use what we already have?
Start with the listed household materials. Keep the basic setup small and ask a grown-up to choose suitable items before beginning. The stated time is an estimate, so let the observation decide whether you need longer.
What should we record?
Note the prediction, the result and the one thing you changed. Keeping those separate helps a family discuss what happened without turning an activity into a competition.
Must the result be shared online?
No. A conversation at home is enough. If you choose to share, keep identifying details out and follow the grown-up permission line above.
More to try
See all Taz Challenges, or look through the science labs. One place for every why. Ask for early access at aitaz.com