Being cart based, I opted not to have second grade use watercolor for their backgrounds - rather we drew interesting line designs with crayons and filled white space up with color. We didn't get a chance to discover new colors that happens when mixing paint, but we did get the chance to categorize our crayons by temperature.
When our pages were colored, second grade practiced drawing dinosaurs. I had put together some packets of dinosaur pictures as well as how to draw pages. Here are a few pages I got from Dover Publications.
How to draw a Brachiosaurus
How to draw an Albertasaurus
We next discussed our parts to composition and created a prehistoric silhouette over our crayon designs with black construction paper.