One Day Lesson: White Charcoal Drawings
Students discussed value and focused on the highlights rather than the shadows for this drawing.
I also demonstrated how the artist can use negative space to help guide the drawing process. For example, I ask what shape the negative space between the arm and body are creating, when the students see this you hear "aaaaaah..." and you see the light bulbs turning on, hehe.
We actually went into a pretty in depth discussion/demo of how to draw objects from observation.
Proof is in the pudding.