When the short, cocky Puerto Rican teen-ager first wandered into the gym of Manhattan's Joan of Arc Junior High School on West 93rd Street, no one bothered to ask him why he had come. The evening boxing class—an effort to keep potential delinquents off the streets—was in full swing. Physical Education Teacher James O'Tarrell. 28, simply assumed that the boy was just another pupil. Then the time came for the class to roll up the mats and leave. Instead of helping with the work, the boy stood on the sidelines and jeered.
When Instructor...