I bought some chalk today, and after some experimenting I decided to have a go at an exercise in one of the art books which I bought. That is to take a photograph and attempt to copy it upside down. This is the result, which frankly I am both amazed and thrilled at.
It is a sketch in Chalk, fixed with spray as it's in my moleskine book. I am absolutely astounded with this - I drew it! I tried to draw the wife a few days ago, and the results were less than convincing, don't go hunting on the site, the pictures are not even worthy of that. The book I got is wonderful, I'm a convert, the simple act of turning a photo upside down works!
The thinking is that if you draw a face, your brain gets in the way, it interprets what it sees, 'nose', 'ear' and so on - and one draws the symbols, not the patterns of light and dark. This exercise is a first step to disconnecting the symbolic part of the brain and demonstrating to the student that it's the powers of observation which are the biggest impediment to progress.
It makes a sort of sense, though it does not stop it being magic.