Reflection: Safety Group Assessment: Triangle Congruence and Proof - Section 1: Warm-Up


My goal in discussing #1 on the warm-up was to develop a shared understanding of exactly what is needed to write a sufficient proof.  I wanted students to better grasp why a proof would receive an A, B, C, D, or F and, more importantly, why.


Before I facilitated this whole-class discussion, I had students share out in their groups the grade they would assign to the sample proof and why.  I told groups that they had to come to consensus about the grade and then share this grade with the whole class, which I recorded publicly.  We listened as groups defended why they had given the sample proof a C, for example, while others had given it a D.  I then publicly graded the sample proof while talking through my own reasoning of the proof (I did this as if modeling a “think aloud”) to try to call attention to exactly what features were necessary for a high quality proof.

  Surfacing Students' Notions About the Features of Proof
  Safety: Surfacing Students' Notions About the Features of Proof
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Group Assessment: Triangle Congruence and Proof

Unit 7: Discovering and Proving Triangle Properties
Lesson 8 of 10

Objective: Students will be able to assess the quality of other students’ proofs and identify specific changes for improvement. Students will be able to use precise definitions of geometry terms and special triangles/quadrilaterals to draw logical conclusions.

Big Idea: By analyzing other students' work, students will gain an understanding of the features of high-quality proofs while developing habits of mind.

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10 teachers like this lesson
Math, Geometry, Triangles, reasoning and proof, Triangle Congruence, triangle similarity
  80 minutes
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