However, it is one of the hardest to teach to kids because going slow is not in their vocabulary. They want to finish the project now and they don't always want to take the time to layer the color and let it magically blend together. So the ones who really succeed at watercolor are the students that have the most patience.
For their final project they could pick any picture from my pile and then they had to paint it but they could not use black. So my goal was to try to get them to think about how to layer colors to get the dark colors that they may need. Also in watercolor you don't always have to use the right colors to get the best picture. A few of my students found this to be very true.