Been getting a little heavy around here with classroom management, so let’s toss out something inconsequential:

  1. How People Count Cash? Turns out they don’t just talk differently in other countries. Also turns out Afghanistan has us beat on style.
  2. Old Spanish Castle Optical Illusion. Which blew our collective mind. To keep this inside the PowerPoint family (if you don’t want to mess with Java in the middle of class) put the inverted image on one slide and the black-and-white image on the next in exactly the same place. Look at the first for thirty seconds and then advance the slide.
  3. F–k Grapefruit. Pointlessly profane but completely cool. I blocked off the cartoonist’s suggestions and had them toss out their own, which turned into a total melee, students throwing stones at each other over the right y-coordinate for cranberries.

    I realize this is totally soft math but I’ll absolutely defend the value of having these kids reframe their daily lives in mathematical terms. No one had considered fruit like this until today.

  4. Karate Slow Motion. A man shatters a brick at 4,000 frames per second, his entire forearm reshuffling itself grotesquely in less than a second. The kids insisted it was fake. I told them it wasn’t but I wished it was. Horrifying stuff.
  5. 41 Hilarious Science Experiments. Hardest I’ve laughed in several months.

And now back to your regularly scheduled handwringing.

2011 Aug 26: This is Dan from the future. It’s bizarre coming back to these posts where I didn’t realize I was teaching math with things like the tasty / easy graph. At this point, I’m still filing the things that will eventually define my career under a “Miscellaneous” category. I mean, look at that. The title of this post is “Anyway.” Like the tasty / easy graph isn’t one of the best introductions to the Cartesian plane ever. This is such a weird time capsule. Anyway. Here’s JL with some great comments on classroom implementation:

We started by graphing fruit on a coordinate plane where the y-axis ranges from “Tasty” to “Un-tasty” and the x-axis ranges from “easy to eat” to “difficult to eat.” Students were given 3 sticky notes and told to write a different fruit on each one. Then they went up and graphed them. They were asked to defend their ordered pair. If a student put Pineapple on the “easy to eat” side, there was an uproar of argument. Kids got really, REALLY into it.

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 can’t believe I still watched that karate one after your comment. And yet, I did. And now it will haunt my sleep tonight.

    Can we go back to talking about classroom management now, please?

  2. Now that thar is some good classroom management!

    Whip out that Spanish castle image at just the right moment and I’m sure that I’ll get my classroom dead silent for at least 20 seconds (of course, then followed by gasps of amazement and overall chatter). The karate clip should be equally spellbinding.

  3. @ Rich (and by extension, Dan): “Now that thar is some good classroom management!”

    BINGO! Although, still not a universal.

    I’m always a fan (note: not biggest fan, not Kathy Bates like, no matter what you may say about me) of taking the odd and working some linguistic magic to make it all seem “valid” and “appropriate” for [insert content area] class.

    Welcome back!

  4. Being A computer tech at a school I am well versed in XKCD and quite surprised and delighted to see it.

  5. I must share the kudos…. my students love you. OK, well, more accurately, they love it when I show the content (videos, images, etc.) that you share. To give a slight explanation – this is “staff appreciation week” at our school (in this case staff = all employees), and today I had some 6th graders who slipped thank-you cards under my door. One of them said, “I love math and I really love your cool videos.” Alas, if only I had generated math teacher content on YouTube. But instead, he just meant the cool and more or less random content that I throw in every now and then. I must admit that you’re just one of my number of sources for this cool stuff (I particularly like my StumbleUpon toolbar in Firefox), but most recently my students have been wowed by the “How People Count Cash” video and the “Old Spanish Castle” image.

    Note: this is NOT a math methods post!!