Because of gravity, liquid usually flows downwards rather than upwards. So how is the coloured water climbing up the paper towel?

Capillary action is a process during which a liquid, like water, moves up something solid, such as a tube or porous material. Porous means something with a lot of small holes.

Capillary action is very important in nature because it’s how plants take in and distribute the moisture they need to grow. The water enters from the roots, and moves upwards to different parts of the plants using tiny tube structures.

CAPILLARY ACTION - KIDDLE

CAPILLARY ACTION - SCIENCE ABC

Primary colours are the basic building blocks of colour. By mixing primary colours together you can make all the other colours! But did you know that the primary colours of pigment are different from the primary colours for light?

The physical substance of colour (whether in plants, paint or printing ink) is called pigment.
The primary colours of pigment are red, yellow and blue. 

Food dye is a kind of edible pigment. In this experiment, we mixed the primary colours to create the secondary colours of pigment: orange, purple and green.

Light is the purest form of colour. All the colour we see in the world is created by light rays bouncing around! The primary colours of light are red, blue and green. 

Take it further…

• Now that you have mixed colours with pigment, try mixing the colours of light with this flashlight and shadow activity from Fizzics Education.

• Let Professor Astro Cat introduce you to light and colour with Flying Eye Books and National Geographic Kids.

• Explore the science of light and colour in depth with Pokapū Akoranga Pūtaiao, the Science Learning Hub of New Zealand.

• Try 7 Ways to use Food Colouring in Play with Powerful Mothering