SAS-sy Triangles

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Students will be able to identify when and how to prove triangles congruent using SAS congruence theorem.

Big Idea

In this student-centered lesson, students will explore and explain why the SAS congruence theorem works to prove triangles congruent.

Do Now and Vocabulary

15 minutes

This Do Now reviews identifying corresponding parts of congruent figures and focuses on using algebra. 

The first page of student notes introduces the idea of an included side using student-created drawings.  To help students differentiate angles and sides I highly recommend having students use highlighters, makers or colored pencils for the student notes in this lesson. The reflections in this lesson also discuss how to use shading techniques. 

Triangle Proof Project

5 minutes

In today's lesson, you may want to give students time to pick their partners and develop a schedule for when and where they will be completing their video.  The documents for this project can be found, here.  This project can be completed throughout the unit or done in it's entirety after completing all the unit lessons. 

Exploration #1 and SAS (MP8)

25 minutes

Practice/Homework and Exit Ticket

15 minutes

A practice proof using SAS is provided for teachers to guide students through.  One way to go over this proof with students is to complete the flow-proof with them, and then ask them to complete the 2 column proof (or vice-versa!)

Students can work on the practice proofs in class or for homework.  Students will use MP #3 to complete this assignment.

The exit ticket  asks students to identify which corresponding angle or segment will allow for a proof of SAS.  This reinforces a key vocabulary word, included side.  If time remains in class, this is definitely an important topic to review with students.  An extension would be to ask students which sides would provide us with SSA, and what does this imply?