Marc discusses the concepts of Light, Value, Edges, and Contrasts in an opening introduction to deeper learning on these topics in drawing. Master these concepts and ideas intellectually, before moving forward to practicing these elements in drawing!
The forms used can be bought at NASCO (I have no financial interest nor do I receive any commission from NASCO).
https://www.enasco.com/t/Arts-Crafts-Materials/Drawing-Drafting-Writing/Drafting/Geometric-Solids