Draw several of the basic forms with their cast shadows falling on a variety of textured surfaces.
Draw several objects with their cast shadows as they would appear first in direct light, and then in diffused light.
Next, go back to your drawings and indicate proximity shadows wherever you can see the contact points between the objects and their cast shadows.
Draw objects with cast shadows that describe the environment and the object's relationship to it.
Draw an object in direct light with a cast shadow and in diffused light with a cast shadow.
Draw an object with its proximity shadow. One end of this object has a proximity shadow; the other doesn't.
Draw an object in the cast shadow of another object. An object in cast shadow looks the same as it would if seen in diffused light, only darker.
Draw objects whose cast shadows describe the texture of their environment.
What's wrong with this picture? How do we get cast shadows to cross? How many light sources do we have? Why do we have only one cast shadow per light source?