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

Clip 16/19: Modeling through Geometry: Lesson Part 4C


Molly McNinch circulates among her student groups, challenging them to refine and improve their visual representations: “your diagram's really great ... it would be even better if you could see the dashes.” Molly encourages her students to connect the fictional students’ work to their group posters: how did each fictional student’s work connect to and extend their thinking?

Teacher Commentary

There was one group in particular who was struggling with just, "How do I relate them all?", and so I set it up, I gave them the triangle, and then I gave them the values for that piece, and then I said, "Okay. We're finding this distance between the narrow diameter and the center of the circle, and then that whole piece is giving us our roll radius." Trying to focus them and make it something they've seen before to help pull that in, to guide them towards what they are producing.