This is a 27 page PowerPoint presentation on Value. It describes value, shading, hatching, cross-hatching and stippling and gives examples. It then goes on to show how to create value with four different medias: pencil, charcoal, pastel, and pen and ink. It walks students through each medium. Students are meant to draw along as you go through the PowerPoint.
This is a great introduction to the Element of Art Value. It is also a great introduction to charcoal, pen and ink and pastel.