Happenings: Easy on the Onion

What is seven feet wide, made out of painted sailcloth, and looks like a giant hamburger with a detachable pickle perched on top? The pop-art answer is a well-done Giant Hamburger by Claes Oldenburg. When the Art Gallery of Toronto recently bought one for some $4,000, students at Toronto's Central Technical High School looked at it with a hungry eye. What a hamburger needs, they reasoned, is ketchup. Someone sent out for a bottle of Heinz; in less time than it takes to shake a slurp out of the bottle, students and teachers had built a 9-ft.-tall, 50-lb....