An art teacher got revenge of sorts on the artist whose Chicago exhibit invited visitors to walk on the American flag. The teacher created an exhibit of his own, offering observers a chance to walk on a caricature of the offending flag display’s creator. It features a life-size sketch of artist “Dread” Scott Tyler, drawn on cloth in the manner of a police outline of a homicide victim. The cloth is on the floor, and a U.S. flag hangs above it on a museum wall. “I was upset by seeing my flag on the floor,” said Gary Mann, 33, a junior high school art teacher from suburban Deerfield, as visitors walked over his artwork at a small Vietnam Museum in Chicago.