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

Clip 15/19: Modeling through Geometry: Lesson Part 4B


Students work together on their status posters, examining and connecting to the fictional students’ work. Molly McNinch’s students consider how they need to correct the fictional students’ thinking and how that correction will help them prepare their visual representation of their group’s work. Molly’s students discuss how to label elements of the poster.

Teacher Commentary

It was a little bit difficult for some students to see the similar triangles relationship, which was our previous unit. It was hard for them to go from the cup to the cone to the triangle to the circle. By helping and trying to guide them towards a, "Well what would this cone look like if you drew it two dimensionally?", I found once they had an image, it was easier for them to say, "Oh, this looks like similar triangles.”