## 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

# Group Assessment: Triangle Congruence and Proof

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

## 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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Standards:
Subject(s):
Math, Geometry, Triangles, reasoning and proof, Triangle Congruence, triangle similarity
80 minutes

### Jessica Uy

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