by Colin Adams
I
“My name is Professor Colin Adams and I’m very excited to be here this year. I’m visiting from a little college back east that none of you will have heard of. I want to welcome all of you to calculus, and for most of you who are first year students, to UC Davis. I just want you to know I am here for you all. My focus is on you. Any time, just drop by to see me. My job as a faculty member is to be available for you 24 hours a day, 7 days a week.
Now we are going to start with a quick review of inequalities.”
Joel wrote \( (x-2)/x < 7 \) on the board.
“To solve this, the first thing we do,” he said, “is multiply through by the denominator.” He wrote \[ x-2 < 7x. \]
At this point I raised my hand.
“Excuse me, Professor,” I said, “but isn’t true that if the \( x \) is negative, you have to change the direction on the inequality?”
Joel turned to look at me with an icy stare.
“If you’re so damned smart, why don’t you teach the class?”
And with that he threw down the chalk and stormed out of the room.
Or at least, that’s the way it was supposed to go. Unfortunately, as he was saying his part, another student yelled out, referring to changing the direction on the inequality, “No, it’s not!” And then there was bedlam as students argued whether or not the direction on the inequality should be changed. So when Joel said his piece and stormed out, most of the students couldn’t hear what he said.
But at any rate, I stood up, picked up the chalk and said, “All right I will.” Students said, “What are you doing? Where did the professor go?” I said, “he said if I’m so smart I should teach the class, so I will.” And with that, I finished the inequality and continued to go over background material.
Then I said, “He left these syllabi. I guess I will hand them out.” By the end of the class period, about half the students understood what had happened. But the other half were still asking, “Why are we listening to this guy?” By the next class, after students had a chance to talk, they all understood it was a joke and the rest of the quarter went very well.
II
That project become the two books How to Ace Calculus and How to Ace the Rest of Calculus which have now together sold over 100,000 copies. Joel’s claim was that on average, for jokes that are out there, one in ten can be turned into a math joke. I was skeptical at first, but it turned out Joel was right. Here is an example that is a Joel original.
Two calculus students are walking in a field and they come across a big deep hole, so deep they cannot see the bottom in the darkness below.
“I wonder how deep it is,” says the first.
“Here. Help me roll this railroad tie over the edge,” said the second. “Then we can count how long it takes to hit the bottom and use calculus to determine the depth.”
So they roll the railroad tie over to the edge and push it over. As they are counting the seconds, they are surprised when a goat suddenly runs up to the edge and dives over.
“That was weird,” said the first, as they peered after it.
Then from off in the distance they hear a voice.
“Excuse me,” yells a farmer from the edge of the field, “but have you seen my goat?”
The students look at each other, and then the second yells back, “Yes, a goat just jumped in this hole.”
“Oh, that can’t be my goat,” yells back the farmer. “My goat is roped to a railroad tie.”
Colin Adams is Thomas T. Read Professor of Mathematics at Williams College, Willamstown, Massachusetts. He writes “Mathematically Bent”, a column for the Mathematical Intelligencer, and is the author of The Knot Book, acclaimed for its lucidity on advanced topics in knot theory. He is coauthor with Joel Hass and Abigail Thompson of How to Ace Calculus and How to Ace the Rest of Calculus. He has been a fellow of the American Mathematical Society since 2012.
