Mix Your Own Rainbow

Make every colour in the rainbow from just red, blue and yellow

Materials

Cardboard for cutting large rainbow shapes
Heavyweight cardstock as an alternative
A box cutter or strong scissors for cutting the shapes
Poster paint in red, blue, and yellow, plus plenty of white (and a little black if you want to explore shades)
Glass jars for mixing, so the colour is visible as it changes
Brushes in a few sizes, foam rollers, and sponges
Palettes or extra jars for mixing
Glitter
String, twine, or ribbon for hanging
A hole punch
A drop sheet or table covering