Unit 2:

Congruence

Geometry is a way to understand the real world around us by basing arguments on concrete referents, modeling relationships, and applying mathematical principles to understand geometric properties and concepts using objects, drawings, diagrams, and actions. 

The Story of Geometry - Unit 2: Congruence (Up to 23 days)

Students began working with transformations in 8th grade.  Unit 2 extends their knowledge to transformations with more shapes and then connects congruence proved through transformations to triangle theorems (and formal proofs).  Students stay in the coordinate plane as they transition to examining transformations and triangle congruence, the two big ideas of the unit.  Supporting standards are embedded as they provide a conceptual framework for understanding the work of the big ideas; these supporting standards can also be explored in greater detail for added depth.  After exploring rigid motions generally, students explore triangle congruence specifically and how the two are related.  Students conclude the unit by comparing transformations that do and do not preserve distance and angle, which acts somewhat as a transition to the next unit on Similarity.

Unit 2 & The Need to Examine Claim 3

Most of the geometry course is tested in Claim 3, Communicating Reasoning: Students clearly and precisely construct viable arguments to support their own reasoning and to critique the reasoning of others.  Communicating reasoning should have begun in Unit 1, and it should be evident in instruction and assessment throughout this unit also.  Students should be primarily engaged with SMP #3: Construct viable arguments and critique the reasoning of others.  Teachers should devote time at the beginning of the year to understand  Claim 3 for themselves, especially the Assessment Targets, Task Models and Examples.

Vocabulary, Tools & Developmental Notes from SBAC

Claim 3, Communicating Reasoning: Students clearly and precisely construct viable arguments to support their own reasoning and to critique the reasoning of others.

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