SSS for Real

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

Big Idea

Student use their own decorative congruent triangles to learn why SSS congruence works.

Do Now

10 minutes

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

Triangles Proof Project

5 minutes

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. 

Pair-Share and Vocabulary

25 minutes

Exploration #1 and Proofs with Congruent Triangles

25 minutes


10 minutes

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

Student Notes - SSS for Real

Exit Ticket

10 minutes

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.