“A Trash-Talking High School Math Teacher”

The story broke online: the express lane isn’t faster. Jaws hit the floor. It made a few laps around the blogosphere while the MSM played catch-up. 72 hours later, I was in front of a camera, explaining the regression to a reporter for CBS in San Jose who in turn challenged me to a race down the checkout lines.

Here is that (two-minute) clip:

Click through to view embedded content.

Three takeaways:

  1. Slow news night.
  2. Everyone has an opinion on this one. Most people also have a demographic they are particularly loathe to find ahead of them in line.
  3. This visceral, widespread reaction to nothing more than a) a clear picture, and b) a concise question will do nothing to make my WCYDWT evangelism less insufferable. Apologies in advance. This isn’t the only way to teach, but it is a fun way.
I'm Dan and this is my blog. I'm a former high school math teacher and current head of teaching at Desmos. He / him. More here.


  1. I hate it when you think you’re presenting an interesting question to a class and they come back with, “Oh, I saw this on TV!”

  2. I like how the adjective he picked for you was “trash-talking.” Of all things. :)

    And agree with @Hemant – it was well-explained even though it was so succinct. And awesome how your graphics were so slick they just used them.

  3. Yeah, as much as I complained about your graphic before, it worked fine on the TV clip. It just needs the context of where you are and what the red things are.

    Trash talking, that’s pretty funny.

  4. Yeah, “trash talking.” I can’t believe they went with that descriptor. At the same time, I guess I can’t really refute it either.

    Oh yeah, and I couldn’t help feeling just a touch vindicated when they used my cough drops for the broadcast.

  5. I think you should do a study on height and success. I have always heard that taller men are more successful. Of course that means first defining success, but … hmmmmm. You are tall and successful. Is this a math problem?

  6. Fantastic work!

    I’d be curious if this would play out across other supermarkets. Perhaps a bigger chain? I wonder if there’d be a difference for length of tenure of cashier?

    Good stuff. Thanks for making math applicable.

    Chris Craft

  7. They contacted me through my blog’s contact form and in a Twitter reply. Apparently, their reporters trade links on Facebook, which was where they found my piece. The reporter couldn’t trace it farther back than that, though.

  8. I took your idea and put a Language Arts spin on it. The other day my kids journaled on this question:

    Why does Fareway (local grocery store) have a limit of 10 items in their express lane and Wal-mart let’s their express lane users go through with 20 items?

  9. When I saw it on reddit and kottke I was thinking “this is getting pretty big.”

    I agree the graphics work well in the context of the video and description of the problem. In fact, it fits the report perfectly.

    I liked the varying points of view from all these sites (and the news report). You can see some of the attitudes the public has towards math / high school, whether they be good or bad.

    Don’t let the fame go to your trash-talking head.

  10. Now I can sleep. Phew! My list of life’s mysteries is officially lessened by one.

    Back that up. When I lived with the guy five years ago, he figured this one out people. Slow news? Nah. Old news.