In 2001, I was a junior at the Bronx High School of Science in New York City. On the morning of September 11th, I was sitting in my second period AP US History class, taught by Dr. Melvin Maskin. On days when he was feeling particularly enthusiastic about a lesson, he’d scrawl things like, “The Doc is IN DA HOUSE” on the blackboard. He was always doing things like that: making silly jokes or referencing song lyrics in tests, to get us excited about settling in for a class period of history.