I was teaching a life drawing class recently, and I came up against one of the main issues that gives me qualms about teaching at all. My student was doing something which he thought was wrong, and he asked me about it. From a certain perspective, having to do with the mechanical representation of the optical facts, he was correct. What he was drawing was wrong. But the art teacher telling the student that some quirk is wrong rankles with me. So I told him what I really think.