This year, I wanted to teach it, but the thought of a 30 minute kindergarten class watercolor painting in their classroom gave me nightmares. I taught the lesson as usual. I substituted watercolor paper for 80lb. drawing paper and told the students to color in everything nice and hard with crayons.
The next art class, we put the finishing touches on our crayon drawings and crumpled them up! I prepped a tub of blue tempera mixed with water.
Students came up to the tub individually and we dipped their papers in the blue water. I set them on a dryrack I had pulled into their classroom. The next day they were completely dry and looked beautiful. It solved the 28+ kids painting in a classroom for 30 minutes problem and the turned out really cool!