An accomplished novice wonders about the challenges of depth over breadth. For musings on parenting and technology, check out bedtimebits.wordpress.com

I used this silent video today for a stand and talk as part of 8th grade rigid motions. I asked if anyone knew what the sum of the angles of a triangle are. Maybe 1/4 of the class raised their hands and knew it’s 180 degrees. I said that there are a lot of things we know in math, but often we don’t ask why. I asked if anyone knew why the angles add to 180. Crickets.

Before we had any conversation, I showed the above video 3 times in a row. Students ooed and awed. Some busily started talking to a neighbor, bouncing up and down with, “I get it, I get it.”

Then we broke it down into a whole series of pair-shares.

“What do you assume is true here?

They concluded that L1 and L2 are meant to be parallel. I threw a few extra points on the image, at each intersection point, telling them that these points would help them describe what they saw with more mathematical precision.

I then paused here and pairs described everything they had seen. Students talked about corresponding angles, congruent angles, translating an angle along a vector.

We repeated the process pausing here and again here:

The rich mathematical language this 13 seconds of video evoked was so exciting to witness. It felt like nearly everything they had learned over the past two weeks of rigid motions was giddily talked about.

Are you a math coach? A technology TOSA? Or someone who loves having students talk about visualizations? If so, I so want more of these gems. For the second year in a row, I am teaching a new grade level, so I don’t have a whole lot of time to seek them out as I can barely keep up with tomorrow’s content, so I am selfishly blogging in hopes that some of you will send me more of these resources connected to my course (8th grade math) or any course before mine.

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