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9th Grade Math - Modeling through Geometry: Circumference of a Cup’s Roll

Clip 18/19: Modeling through Geometry: Post-Lesson Debrief Part 1


In their debrief of the lesson, Molly McNinch and math colleague Jim Karditzas discuss general impressions of how the lesson went. Molly shares that the students came to some “really interesting conclusions,” and were not as stumped or stuck as she anticipated they might be. She and Jim examine the students’ posters for insights, and discuss modifications Molly made to her lesson across multiple periods of the instructional day.

Teacher Commentary

From third period to fifth period, I forgot both times to give them the rolling cups calculator immediately, which I didn't think hurt them at all. I think with third period, they kind of reached a point where they were stumped, and when I pulled in that rolling cup calculator, I think it reengaged them and re-focused them. In fifth period, I thought it actually made for a nice segue into, "Okay. You guys need a little bit extra. Let's give you this tool to use." I think from third to fifth [period], I tried to put more focus on the [fictional] student work as new group mates versus looking at it as three separate solutions. With third period, they thought, "Oh, you're giving me the answers," and so I tried to focus my fifth period and tell them, "These are not solutions whatsoever, but they're just extra partners you can pull from."