Do you want to show students how to change something 2D into 3D??? This is a great lesson with 2 activities ... the first is a value scale and the second is to change a 2D circle in to a sphere! students love this lesson. It teaches students how to make something look real and how to really look!!! The next assignment could be to draw and shade some apples . . . a still life : ) Look at artist Paul Cezanne "Apples in a Bowl".