"This is a two-million-dollar piece of conceptual art. This is bin full of wastepaper. Okay, class, who can tell me what the difference is?" This is just one of the questions trash collectors in Frankfurt, Germany, will be asked when they begin mandatory art classes next month. The classes were mandated after one of the city's sanitation workers picked up a sculpture by the artist Michael Beutler believing it to be a pile of junk. The piece, part of a city-wide exhibit, was later thrown into the city incinerator and burned. A London newspaper reported that the poor befuddled sanitation...