Walking water and colour theory

A great little science experiment that demonstrates both colour theory* and the capillary action (which is how water moves up plant stems.) The water walks ‘magically’ from cup to cup and mixes the colours as it goes.

*Colour theory is when you use primary colours like red, blue and yellow to create secondary colours like purple, green and orange.


For example Red and yellow makes orange. Yellow and blue makes green. Blue and red makes purple.

All you need is water, 6 paper towels, 7 clear containers (we used some recycled plastic cups we took home and recycled  from a friends birthday party) and yellow, red and blue food colouring.


First line up 3 empty containers on a tray, then fill the remaining 4 containers with water (over half full)  and mix food colours into each so that you have a line of colours in this order red, yellow, blue and red again. These are your primary colours, primary colours are colours that can’t be made from mixing other colours but you can make new colours when you mix them together.


Line your 7 containers up in the following order 1. red, 2. empty, 3. yellow, 4. empty, 5. blue, 5. empty and finally 7. red.

Take your 6 paper towels and individually fold it twist each one into a strip. Fold the strip in the middle and place it over the edge of two containers. Starting from red to empty. So one end dangles in a coloured liquid and the other dangles into an empty container. Then place another from the empty to the yellow. Do this repeatedly along the row until each container is connected in line of towls.


The paper towls will start to soak up the water and eventually the water will travel up the paper and over into the next container. This is called the capillary action.


If you leave the containers for a few hours eventually all the empty cups will have filled part way up with water. As each of the different primary colours mixes together they form new secondary colours. Your red and yellow should have combined to make orange, the yellow and blue should have made green and the last blue and red should have made purple. This is a lovely visual demonstrstion of colour theory in action.


Once you have finished with you experiment you could freeze the coloured water to make rainbow ice or colourful ice building blocks to play with another day.


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