Not that she had counted, but it was exactly the 5,091st time a student asked Mrs. Lenderson “when will we ever use calculus in the real world?” when she snapped and became the Derivative Killer. Sure, it was a misleading serial killer name. Yes, she always expected to get caught with each adult she captured and put to her deadly trials of mathematics that mostly ended in horrific slaughter. She was okay with that inevitable outcome as long as she could exact her calculated justice. She never expected the US Government to hire her full time to continue her murder spree — not even after she single handedly caused a 70.2% increase in math scores nationwide. It was precisely the kind of difference she had hoped to make when she became a teacher in the first place.