Learn a very simple way to draw a Colour Wheel, using the three Primary Colours; Yellow, Red and Blue.
Start with yellow and then add red over the top of the last bit of yellow, making orange. Continue to use red, then on the last bit of red use blue, to make purple. Then continue using just blue and go over some of the yellow you started with, to make green. The orange, purple and green colours you make will depend on the Primary Colours you started with.
I used three oil pastels in this video.