This super fun experiment is sure to astound your little ones and give them an insight into colour theory and how water can defy gravity and travel from cup to cup. Super fun and easy to do, it just requires a few things and you will see results begin to appear in a matter of minutes.

What you’ll need

  • Small plastic cups or glasses x7
  • Paper towels
  • Food colouring (primary colours)
  • Water

Before you start, get some sheets of paper ready so your kids can write down what they expect will happen during the experiment, and note down their observations as they go.


  • Place the 7 cups in a row next to each other, then fill the 1st, 3rd, 5th and 7th cups about ¾ of the way with water.
  • Add 5 drops of red food colouring to the 1st and 7th cup.
  • Add 5 drops of yellow food colouring to the 3rd cup.
  • Add 5 drops of blue food colouring to the 5th cup. Add more if you wish but make sure all cups have equal amounts of respective colours in them.
  • Take a sheet of paper towel and cut in half. Fold that in half lengthwise, then fold in half again. Trim the ends so that it can sit nicely without too much excess sticking up in the air between each cup. Repeat til you have 6 paper towel strips.
  • Place one half of a prepared paper towel strip into the 1st cup, and the other half into the cup next to it. Then place another paper towel half in the 2nd cup and fold over into the 3rd cup. Continue this until you have placed the last towel draped from the 6th to the 7th cup.

Your kids should quickly be able to see the coloured water beginning to crawl up the paper towels, and soon the water will have transferred over into the next cup. They will also notice the colours beginning to mix in what used to be the empty cups.

Keep observing over the next hour or so then review their observations. Did they expect the result? Are they surprised by the colour mixtures? Do they know how the water managed to travel from cup to cup?

How does it work?

The water is able to move up the paper towels through a process called capillary action, the same method a plant can absorb water and drag it up through its stem and up to its leaves. The paper towel is made of fibers, and the gaps between these fibres act like capillary tubes that the water is able to be pulled up through. The water is also able to work against gravity due to the attractive forces between the water and the fibers of the paper towel.

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