I loved doing this in art class. Art With Mr. E: Line Design w/Shading - Grade Very cool, fun art shading project from Art With Mr. E. he's an elementary art specialist. Try this with your kids (but I think grown ups would enjoy this too).
Painting with Watercolors, Glue and Salt. This will be a fun project this summer, just paint the canvas with watercolors. add some kosher sea salt (coarse is better than fine salt) and some glue splotches!