Art: Kindergarten color theory

I started teaching art in kindergarten a few months ago when the lead teacher went on maternity leave. She's back, but I'm still there helping out. I've been focusing on color. We did rainbows and coffee filter prints and several other fun things. Here, they colored tissue paper with a primary color marker, and then were given the choice of a bordering secondary color (for instance, if they used yellow, they could then use green or orange) to paint dots with a matchstick. These then, later, hung in page protectors from the ceiling pipes to catch the light.