Richard Serra is known for his giant installations composed of sheets of metal which self-support solidly although the viewer may perceive them as unstable and ethereal. Serra first discovered that a heavy steel plate could be supported by the corner of a room. Thus, the space of the room becomes part of the sculpture. By leaning several steel plates one against each other in a cycle Serra finds another way of displaying them securely with different rotational symmetries. These experiments can be made using small cardboard plates. Serra also uses simple geometrical curved surfaces, which includes spheres, toruses, ellipses, cones and cylinders. Easy ways to play with these surfaces in the classroom is the use of plaster bandages which provide students an exciting geometry class.