All Things Considered pays tribute to a great calculus teacher, Louis Leithold, author of a classic calculus textbook.
So does this LA Times obituary:
The biggest day of the year, next to the exam, was when Leithold taught the fundamental theorem, a central idea of calculus that says that the sum of infinitesimal changes in a quantity over time equals the net change in quantity.
Usually a casual dresser, he would wear a jacket to class. After a proper buildup, he removed the coat to reveal a T-shirt emblazoned with, what else, the famous theorem.
He died at age 80, days before his Malibu High students were to take the AP Calculus exam.