Step 1: Items Needed
Crumpled scrap paper: actually, any oddly-shaped object will work (small toys, found objects, twigs, etc.) but I recommend crumpled scrap paper because it is readily available, free, and will always be a random, unique shape. The type of paper does not matter. You can crumple, crinkle and even partially tear it as you wish. The more interesting the shape the better.
Light source: a desk lamp or flashlight will work. It does not have to be very bright, just enough to cast shadows onto the drawing surface.
Pen: I used a fountain pen, but a felt-tip pen, ballpoint or marker will also work. Anything except pencils; no erasing is allowed for this exercise.
Step 2: Step 1
Trace parts of the shadows to create random squiggles. You must use a pen for this so that the squiggles can not be erased later.
You can move the light, the crumpled paper or your drawing surface. Make as many squiggles as you like.
Step 3: Step 2
You can turn each squiggle into an individual piece or use them together to make a bigger or more complex picture.
It does not matter what it looks like, or if the finished product "looks good" or "makes sense." The important part is to look at each squiggle and decide how to use it.
Step 4: Additional Tips
For an extra challenge, you may want to center your drawings around a theme (e.g., "animals only" or "holiday images") or restrict some things (e.g., "no trees" or "no cartoons")
This exercise can be modified for a group of people, such as a class. Each person creates their squiggles then passes it to someone else in the group to complete. Alternatively, if you use a large enough drawing surface, the group can work together on one piece consisting of many squiggles .