WR = Warm Red (Cad. Red)
WY = Warm Yellow (Cad Yellow)
WB = Warm Blue (Cerulean Blue)
CR = Cool Red ( Alizarin Crimson)
CY = Cool Yellow (Lemon Yellow)
CB = Cool Blue (Ultramarine)
You can use any combination of the three primaries, just make sure of the relative temperature comparisons. I print this out on an 11"x 14" sheet of watercolor paper, using my Epson R1900 so the ink doesn't bleed. We use watercolors. The student paints the outside circles the two primary colors we will be mixing. The centers of the overlapped circles are for the secondary mixtures. It's interesting to see how the secondary color in the center changes depending on the warm and cool primary choices.
Please feel free to use this if you are interested.