# SSS for Real

Lesson 3 of 10

## Objective: SWBAT identify when to use SSS to prove that triangles are congruent and will also prove that triangles are congruent using SSS.

#### Do Now

*10 min*

Students will solve a review question using exterior angle theorem learned from a previous lesson to start class.

#### Resources

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#### Triangles Proof Project

*5 min*

To create a common thread between this lesson and the subsequent lessons on triangle congruence theorems, you may want to introduce the summative project for this unit, the Triangle Video Proof Project, in this lesson. In this project, students are required to write a challenging triangle proof, present and film this proof and also then present their proof to the class.

To use this a whole unit project, you can ask students to complete specific tasks found on the rubric (which can be found in this lesson) each day. An option would be to to have students complete a practice video using a proof, completed in class, from their students' notes.

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#### Activity/Homework

*10 min*

Students can work on the two proofs as an in-class assignment or for homework.

*Student Notes - SSS for Real*

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#### Exit Ticket

*10 min*

Students will complete a writing assignment for the exit ticket - asking them to explain two key ideas relating to congruence, SSS and rigid motion. You can leave extra time to review this assignment in class or collect this assignment and give feedback for students.

#### Resources

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- UNIT 1: Introduction to Geometry: Points, Lines, Planes, and Angles
- UNIT 2: Line-sanity!
- UNIT 3: Transformers and Transformations
- UNIT 4: Tremendous Triangles
- UNIT 5: Three Triangle Topics
- UNIT 6: Pretty Polygons
- UNIT 7: MidTerm Materials
- UNIT 8: Circles
- UNIT 9: 3-D Shapes and Volume
- UNIT 10: Sweet Similar Shapes
- UNIT 11: Trig Trickery
- UNIT 12: Finally Finals

- LESSON 1: Time for Triangles
- LESSON 2: Time for More Triangles
- LESSON 3: SSS for Real
- LESSON 4: SAS-sy Triangles
- LESSON 5: AAS and ASA Fun
- LESSON 6: HL and More Practice with Proofs
- LESSON 7: Isosceles Triangles Forever
- LESSON 8: On the Plane - Coordinate Geometry Proofs
- LESSON 9: Overlapping Triangles
- LESSON 10: Tremendous Triangles Projects