#### MAT-HS.G-CO.10.a

 MAT-HS Targeted Standards(G) Concept: Geometry(CO) Domain: CongruenceCluster: Prove geometric theorems MAT-HS.G-CO.10.a Prove theorems about triangles. (Theorems include but are not limited to: Measures of interior angles of a triangle sum to 180 degrees; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.) (Focus on proving for this proficiency scale)

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## Proficiency Scale

 Score Description Sample Activity Advanced In addition to Score 3.0, the student demonstrates in-depth inferences and applications regarding more complex material that go beyond end of instruction expectations. Analyze a proof with errors and make corrections - 3.5 In addition to Score 3.0 performance, the student demonstrates in-depth inferences and applications regarding the more complex content with partial success. Proficient “The Standard.” The student demonstrates no major errors or omissions regarding any of the information and processes that were end of instruction expectations.   Identify relevant given information Arrange reasoning in a logical sequence Support reasoning using appropriate justifications (theorems, postulates, definitions, etc.) Midsegment of a Triangle Proof Triangle Interior Angle Proof Prove a Triangle is Isosceles 2.5 The student demonstrates no major errors or omissions regarding the simpler details and processes (Score 2.0 content) and partial knowledge of the more complex ideas and processes (Score 3.0 content). Progressing The student demonstrates no major errors or omissions regarding the simpler details and processes but exhibits major errors or omissions regarding the more complex ideas and processes (Score 3.0 content).   partially prove but reasoning has gaps, steps missing, incorrect reasoning, etc. recall theorems, definitions, and postulates fill out justification given a statement Given a statement, the student can fill out the justification.  (skeleton proof) 1.5 The student demonstrates partial knowledge of the simpler details and processes (Score 2.0 content) but exhibits major errors or omissions regarding the more complex ideas and procedures (Score 3.0 content). Beginning With help, the student demonstrates a partial understanding of some of the simpler details and processes (Score 2.0 content) and some of the more complex ideas and processes (Score 3.0 content). - 0.5 With help, the student demonstrates a partial understanding of some of the simpler details and processes (Score 2.0 content) but not the more complex ideas and processes (Score 3.0 content). 0.0 Even with help, the student demonstrates no understanding or skill. -

## Resources

 Web Vocab