What are primary colours?
Primary colours are the ones you cannot make by mixing others, and in a child's paint set they are red, yellow and blue. From those three you can mix most of the colours on a simple colour wheel, which is why they are the usual starting point.
It is worth knowing that red, yellow and blue is a teaching convention rather than an exact law of nature. Real pigments are never perfectly pure, so no three paints behave like perfect primaries. There are three systems you may hear about:
- Painting and drawing at home: red, yellow and blue are taught as the primaries, and they work well enough for children's poster paint.
- Printing inks and many dyes: cyan, magenta and yellow, with black added in printing, which is why printers use CMYK ink.
- Screens: red, green and blue light, mixed together to make every colour you see on a phone or television.
What are secondary colours?
A secondary colour is what you get by mixing two primary colours: red and yellow make orange, yellow and blue make green, and red and blue make violet. Six colours, three simple pairs.
The amounts matter as much as the colours themselves. A mix with more yellow than blue gives a bright yellow-green, while more blue gives a deeper blue-green. Encourage children to add the darker colour a little at a time, because it is easy to add paint and impossible to take it back out.
What are tertiary colours?
A tertiary colour is made by mixing a primary colour with a secondary colour that sits next to it on the colour wheel, giving names such as red-orange, yellow-green and blue-violet. There are six of them, and they fill the gaps between the colours children usually name first.
Tertiary colours suit older children, often around eight and up, who can plan a mix rather than simply enjoy the mess. Ask them to make a colour that is orange but more red, or green but greyer, then name it together. That small step from mixing to describing is where real colour vocabulary grows.
Why does a paint mix turn muddy or brown?
A mix turns muddy when all three primary colours end up in it, even in small amounts, or when opposite colours on the wheel are combined, such as red with green, blue with orange, or yellow with violet. Those opposite pairs are called complementary colours, and together they push a mix towards grey or brown.
Two practical culprits matter more than theory when children are painting: a brush that has not been rinsed, and water that is already dirty. Fresh water and a quick wipe of the brush between colours will do more for a bright mix than any colour wheel on the wall.
How do you set up colour mixing at home?
You need very little: three blobs of paint, a white plate or palette, a brush or two, and a cup of water. A white plate shows colours honestly, and an old ice cube tray gives six small wells for six experiments.
Try this: put a drop of red food colouring in one cup of water, yellow in a second and blue in a third. Half-fill three more cups with clear water and let your child mix two spoonfuls at a time, red with yellow, yellow with blue, red with blue. Then try all three together and watch the colour dull towards brown. It is the same lesson as paint, with no brushes to wash.
Name what you see as it happens: that is a green with plenty of yellow in it, that one is heading towards grey. Naming colours and their shades out loud is the most useful thing you can do, and it sits at the heart of how to teach colours to toddlers and preschoolers at any age. The same playful, hands-on approach is why learning through play sticks so well.
Does Hue Rush help with colour mixing?
Not directly. Hue Rush is a free iPhone colour-matching game that trains colour perception, focus and reaction speed, with Classic, Time Attack and Blind modes plus daily challenges. What it practises is telling colours apart quickly and accurately, which is useful groundwork: a child who can spot the difference between two close greens will judge a mix with more confidence.
It does not teach mixing itself, and no game replaces getting your hands on real paint. Think of it as a few minutes of colour spotting that supports the messy work at the kitchen table. If you are weighing up which colour apps earn their place, our checklist for choosing a good educational app covers the questions worth asking.
Common questions
Is it red, yellow and blue, or cyan, magenta and yellow?
Both describe real systems. Children's paint is taught with red, yellow and blue because that is what most paint sets contain, while printing inks and many dyes use cyan, magenta and yellow, with black added in printing. Screens use a third system entirely: red, green and blue light.
What is the difference between secondary and tertiary colours?
Secondary colours come from mixing two primary colours, giving orange, green and violet. Tertiary colours come from mixing a primary colour with a neighbouring secondary colour, giving six in-between names such as red-orange and blue-green.
At what age do children learn colour mixing?
Many children enjoy naming and mixing colours from around three or four, and can plan a mix deliberately by about seven or eight. Tertiary colours and colour wheels usually land best from around eight onwards, when children can hold two ideas in mind at once.
Why did our blue and yellow make grey instead of green?
Usually because a little red crept in from an unrinsed brush, or because the blue and yellow were not pure to begin with. Many art paints contain a blend of pigments, so results vary between tubes and even between batches.
Do we need special paints for colour mixing?
No. Any red, yellow and blue paint will do, and ready-mixed children's paint is fine. Cheaper poster paint often mixes a little duller, but the lessons about primary, secondary and tertiary colours come through either way.