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).
Artsonia is a kids art museum where young artists and students display their art for other kids worldwide to view. This gallery displays schools and student art projects in our museum and offer exciting lesson plan art project ideas.
Going to do this Op-Art Perspective Lesson for my after-school art class, but take a 'falling' photo of each kid and let them add the cut-out to the middle of their drawing. basic lesson via Art is From the Heart: Op Art