I have hung a French horn, bicycle, or set up a collection of different sized
stools and wooden chairs with a strong light shining through them onto a
screen. The students draw the light patterns on the screen. It is "cheating"
but they immediately get the concept and it is much less frustrating for them
and me both than from straight observation.
Before they begin their drawings, I do a quick demonstration piece by taping a
piece of poster board to the screen and drawing the lighted shapes cast on it.
When I turn off the light they are able to see the form from the negative
spaces and get an idea what theirs' should look like. Painting the "form"
black and using blended oil pastels in the newly positive shapes made them
When talking about P/N, I always use the example I think I stole from Betty
Edwards about the shared edges when a cartoon character goes through a wall.
The kids remember that one.
I have used the sighting method a lot. I try to demonstrate it to the entire
class first. I have used an overhead projector to "trace" the lines as we
examine angles and line directions. I take them outside to view receding brick
walls and let them stand and then sit dow to discover how viewpoint effects
the angles. I end up having to help the majority of them with their drawing of
some part of the exterior of the school. I peer over their shoulder and have
them hold up their pencils on the angles, so we are seeing from basically the
same viewpoint. If I can just get across to them to draw what they see in
relation to their pencil held on the vertical or horizontal instead of drawing
it the way they think they see it. Someone has to have a better way!
Good luck! You're gonna need some mega vitamins with that schedule!