Elaborative thinking is the challenge here. Students begin with a single concept and branch out in surprising directions. Promotes flexible thinking!
One activity starts this way: "Suddenly you have turned into a tiny person as big as your thumb. You are wearing glasses. Draw them the size they would be." From there, the challenge goes into other ideas connected to being one thumb tall. "Think of three things you could carry but which would seem heavy." Or, "How big is that hat you're wearing? Draw it." And on it goes.
Students are encouraged to think about 15 different subjects from a variety of angles.