Build confidence in proofs by proving a known property. Pupils explore two approaches to proving base angles of isosceles triangles are congruent: transformations and SAS. They then apply their understanding of the proof to more complex ones involving isosceles triangles.

Concepts

isosceles triangles, congruent triangles, corresponding angles, corresponding sides, transformations

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Additional Tags

math

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Instructional Ideas

• Create envelop proofs from the examples for students to complete before attempting the proof independently
• Form collaborative groups and differentiate by assigning the example proofs to different groups

Classroom Considerations

• Prior knowledge of SAS, geometric proofs, and corresponding parts is helpful

Pros

• The resource introduces proofs gradually based on their complexity, from beginner to increasingly more difficult
• Multiple methods are encouraged

Cons

• None

Common Core

HSG-CO.B.7 HSG-CO.B.8