Show and Tell: Week 33

I show two excellent photo sets and two excellent videos in my class every week. I have no idea why I haven’t made this a regular fixture around here.


  1. Refacing Government Tender

    Don’t deny you ever did this. Pictured here is “Emo Lincoln,” which is spot on.

  2. Youngme/Nowme

    Look, I don’t consider myself an emotional dude. I only the learned the spelling of “emotion” a month ago and internal reconnaissance has yet to discover any beyond “road rage.” Yet I tell you truly that “Youngme/Nowme” obliterated me. I’d like to believe I appreciate Ze Frank’s Internet icebreakers more than the average Web 2.0 fanboy/girl but I probably kid myself.


  1. Nike Soccer

    Nike spot directed by Guy Ritchie, putting you first-person into the world of professional soccer . All sorts of name-brand soccer stars show up, though, as with emotions, I’m only reporting second-hand here.

  2. Syncing Metronomes

    via Jason Kottke, who writes “If you only watch one metronome video in your life, make it this one.” Someone please explain how this happened. ¶ I pinned the video to this study for good measure.

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. That was certainly the best metronome video I’ve ever seen.

    There’s actually some interesting math behind the synchronization though. The same mathematics are used to analyze synchronization of neurons in neuroscience. I learned this in a graduate level class on nonlinear control last semester. A name for the method used is contraction analysis. Here’s a reference for the stout of heart:

    Placing the board on the soda cans so that it was free to roll back and forth was an important part. This creates a physical coupling between all the metronomes based on conservation of momentum. Another important physical effect is friction. Or maybe it’s the wound-up spring supplying energy to the metronome. I need to check the math.

  2. The Nike ad makes me think of an ongoing conversation I have w/ our tech coordinator/teacher edulicious. Our students (and you and me, for that matter) speak the language of buy/sell. Marketing is appealing to us…whatever our comfort level w/ that is, it’s a cultural reality life in the Western world. Instead of pushing back, why DON’T we design lessons w/ this in mind? Aren’t we, in a sense, selling the learning lifestyle?
    Also wondering how The Get Up Kids would feel about emo lincoln.

  3. So – do you use these as a lead into Maths, or are they ‘just’ there to set the tone and get the class enthused?

  4. I too found the metronome video on kottke and coincidentally also showed it to my class. Cool stuff! You asked for a “how” and I’ve been trying to understand that.

    (1) Here’s the official physics paper on it:
    There’s no clippable quotation from that paper. And I don’t know even if I had the time I could tear through it. Maybe.

    (2) Here’s the historical precedent — Huygen’s Clocks.
    From what I can get, this metronome thing is simply this clock experiment speeded up. So you see the synchronization faster.

    (3) And wikipedia (love wikipedia) speaks about the phenomenon it here:

    The relevant passage is: “The accepted explanation for this is that small amounts of energy are transferred between the two systems when they are out of phase in such a way as to produce negative feedback. As they assume a more stable phase relationship, the amounts of energy gradually reduce to zero.”

    Which basically confirms what I thought when I first saw it: energy is transferred from one metronome to the other through the wooden base. The question is why the energy transfers in such a way as to create this “stable phase relationship” (synchronicity). But yeah – I think really working through that physics paper will be the only way to get that answer.

  5. It’s all about the pendulums, baby.

    All the metronomes are set to the same beats per minute, it’s just that they are started at different times. They are out of phase because that wooden table isn’t flexible enough to let the ‘nomes groove to the same rhythm. Putting the ‘nomes up on those cans lets them move. The board they are on rolls on the cans just slightly according to the average swing of the ‘nomes, bringing those behind the collective beat forward a touch and those ahead of the collective beat backward a touch. Pendulums allow that kind of flexibility (and that’s why some musicians swear by pendulum-based metronomes and curse electronic ones). Now that they are shaking together, they fall into sync because their pendulums can shift forward or backward just slightly, while still keeping the same BPM — you don’t notice micro-second shifts in beat. All the pendulums are moving toward the average rhythm, the collective beat, because of the movement of the board on the cans.

  6. Dan,
    Please do comment on how you use these. Are they lead ins to a math topic? Something to break up math topics? Random things to liven up the class and keep interest?


  7. When did Todd start teaching physics?

    Re the queries from Alex and Glenn, in a two-hour block, we’ll spend twenty minutes crunching away at an an opener, after which I’ll show ’em a few photos. After our first instructional block, about halfway through, they get a five-min break and we watch a video.

    If I had found a connection between math and emo Lincoln, believe me, I would have pimped it long before now. Do we discuss these afterwards? Share pieces of ourselves, our experiences, our opinions? Absolutely.

    So while these are rarely mathematical, sometimes just entertaining, they are one of my best classroom management tools.

    Whoops. I knew I wrote about this before. Maybe save me a moment, fellas, and read one of the show and tell posts.

  8. I’ve taken to adding in similar “fun facts” to my class. I was going to create a big long list of them here. Then I was like: Duh, I have my own blog, I’ll do my own post & link back to here.

    Personally, I’ve gotten to know my students much better since I’ve started adding these random clips into my practice. They all assume I spend countless hours scouring the interwebs for these bits. However, I have a few secret weapons:

    1. An RSS aggregator

    In addition to all the fun videos & pics, I swear I’ve found more sincerely educational content off these sites than any other three feeds I subscribe to.

  9. Ditto on the value of these quick (quick!) videos to classroom culture, along with how easy they are to track down with an RSS aggregator (rather, they track you down), along with how transformative and educational they are with the right line of questioning.

    I maintain a pretty wide net, much of which comprises film & design sites, which may not have much interest to you.

    I’m into:

    Among some others.