Scenes from the “Real World” Where Math is Useful

…when you run into a college classmate who dropped out after suffering from health issues. You always meant to write a nice, sympathetic letter of support, but it never crested to the top of your to-do list, and now your long silence seems callous. The classmate sees you, looks away, then marches right up to you and asks, point-blank, the question you’ve dreaded for years:

“Why,” your classmate spits, “does raising both sides of an algebraic equation to an even power potentially introduce extraneous solutions?”

…you’ve already skimmed every worthwhile article in the newspaper. You completed the crossword, the Sudoku, even the word jumble. Grudgingly, you turn to the paper’s last remaining puzzle: the Partial Differential Equation of the Day.

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Mad-Lib Mathematics

To start the year, I wanted to see what my students thought of mathematics. Is it pleasure or pain, hobby or hurdle, adventure or adversity? Or is it something else entirely, something that perhaps doesn’t come in alliterative pairs?

So I gave them a survey, asking them to complete the following six sentences.

  • Mathematics is
  • Mathematics is not
  • Mathematics is useful for…
  • Mathematics is useless for…
  • My favorite thing about mathematics is…
  • My least favorite thing about mathematics is…

Their answers spanned the whole spectrum of attitudes, from rapture to resignation, from joyful to jilted. (Apologies for the alliteration; I can’t contain it. Clearly.) Here’s a small sampling selection smattering collection of their answers, in all their silly wit and strange variety.


…playing with numbers.

…a long word for “maths.”

…the best!

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The Lesson I Learned from Hating on the SAT’s Guessing Policy

Man—I had a whole, scathing essay written and ready to go.

The title: The SAT Changed Their Guessing Policy to Appear Fairer, But It’s Actually Less Fair. “With the ACT pulling ahead in the admissions test Cola Wars,” I wrote, “I struggle to greet the SAT’s announced changes with anything but cynicism.”

I was halfway into the boxing ring when I realized I was on the wrong side of the fight.

This little fable is about the SAT’s “guessing penalty,” and while it’s a tale full of technicalities, I promise it’ll end with a moral. A moral so obvious, it’s surprising.

Or perhaps vice versa: so surprising, it’s obvious. Continue reading

Elegant, Simple, Coherent, and… Oh Yeah, Totally Wrong

In a Labor Economics class, I had a great TA named Peter. He taught me a deep truth about labor markets: namely, that TAs sometimes teach better than professors.

If people looked like bad drawings, he’d look like this:

He also taught me one of the most enduring lessons I’ve learned about economics, modeling, and the limits of theory to explain the social world.

But the lesson wasn’t about those things. Not explicitly. It was about the minimum wage. Continue reading

Letters from a Calculus Class

Dear Newton,

C’mon, dude. You already get credit for the laws of motion, that cool apple story, and the tasty fig cookies. Let me have this.



Dear Student,

I know it stings to fail a test that badly. But hey, silver lining: you’re so far into the area below the curve that you’re practically an integral.



Dear Student,

I’ll put it this way: You don’t seem to understand me yet, but you keep getting closer.


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