The week before classes began, Harold, a high school history teacher, fell off a step ladder and injured his back. For the next three months he was forced to wear a plaster cast around the entire upper part of his body. The cast fit so well underneath his shirt and sport coat that it was not at all noticeable.

On the first day of class, with the cast under his shirt, Harold discovered that he had been assigned the rowdiest and most rebellious students in the whole school. Walking confidently into his boisterous and disorderly classroom, Harold opened the windows and then busied himself at his desk until the bell rang to indicate the beginning of what looked like a very long history class. When a strong breeze started Harold’s necktie flapping in his face, Harold calmly picked up his desk …