Skip to main content


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

Clip 6/19: Modeling through Geometry: Lesson Part 1B


After students rewatch a video representation of rolling objects, Molly McNinch asks them to work in small groups to “create a poster showing your thought process, data, and solution.” She reviews expectations for participation and mathematical discourse, and reminds students that they will need to identify strategies for modeling that will support their justification. Her students get started, engaging each other in discussion about the objects and their rolling behavior.

Teacher Commentary

I work to build my students’ agency, authority, and identity as mathematicians. It's hard as freshmen. I think it's hard in general for high school students. Not that it's hard to teach, but it's hard because I think it goes along with their agency and authority and identity as people. So many students are still discovering who they are. I use my cards all the time and I'll call on someone and they say, "I don't know." Or they'll start to say it and then they'll say, "Oh, no, no, no. It's wrong." And they'll second-guess themselves. I never let my students get away with that. I go, "No, no, no. Tell me. Tell me." I put wrong answers up on the board every single day.