So Happy Together #4

Make the marriage of your digital projector and laptop a happy one.

One Idea:

Use visual callbacks to refresh their memory.

Like this:

We’re talking about tessellations, how squares and equilateral triangles tile your bathroom floor without gaps.

I put up a square / equilateral triangle in Keynote and after they draw the tessellation on their paper, I hit a button and the same thing animates on the screen.

The next day I want to talk about the general case.

Without my digital projector, I’d say, “Okay, so you guys remember yesterday how we saw that an equilateral triangle tessellated the plane? Will your garden-variety, no-account scalene triangle do the same thing?”

No one would contradict my first assumption but only, like, 50% would really remember.

With a digital projector, though, I just copy & paste a slide from the previous day, strip off its animations, and there I have an effective visual callback to the last lesson.

Just like the “Previously on Lost ” introductions, this technique functions even when pushed weeks into the past.

“Remember when we were looking at distance around the Earth last month?”

And they do.

Previous Editions:

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’ve always been a fan of tessellations, but hold them up against verbs and I think they’ll meet their match.

    Action always trumps triangulation.

    Just a shout out to a writing assignment I gave a class once. They hated “words”. They believed “numbers ruled”.

  2. @ken:

    What an improbable tournament!

    After a matched pair of early games in which the unbearably unexciting wordplay of both Passive Voice and Adverbs was soundly beaten by the product of Multiplication’s xperience and some lesser factors, the western division bogged down in a war-of-words between the historically staid OED and those neologisticly youthful Nouns, who were still smarting from that passionate controversy in their first game over some rather unbelievable statistics (one digit in particular kept showing up from Benford’s unruly fans, if you know what I mean).

    In the east (after Juliet set), the ever active Verbs appeared to be breezing through the tourney (with help from their little guys) until they floundered in the semis to the unexpectedly better-than-average triplets of Mean, Median, and Mode. (Subtraction had already proved they were the lesser team by complaining, “we aren’t used to single elimination,” but do the math: with such a negative performance, that fact didn’t make a difference.) Anyway, MMM really threw Verbs for a curve in affine game.

    Yet the Big Easy proved Much Harder. Any correlation between MMM’s earlier games and the finals rapidly approached zero. Against Nouns, a win would be predicated only on perfection, but our heros deviated from Coach Norm’s standard plan to put up some prime numbers. The trio were technically in the game but really just outlying on the court. As the pounding algorithm of the Noun marching band counted down the final arc seconds, our boys had nothing left to given.

    Certainly, one could argue Nouns already should have turned Pronoun this late in the narrative, and in an equilateral world, they would have. But no fancy rhetoric can redefine Nouns’ dominance. I’ve got no axiom to grind with them.

    Still, I felt vindicated when those subjects took their proper place on the winner’s podium; as that handsome and elegant old man presented them their trophy, Nouns shamed their division by failing to recognize Commissioner Euler’s identity.

  3. @stephen

    Good lord, man! Far more than I could have ever hoped. Please feel free to audit more Honors English 12 class anytime.

    Nouns = shame.

    I have the full field of 64 if you’re interested.