1. September 13, 2013 1) Sit. 2) Materials out. 3) Backpacks away
September 13, ) Sit. 2) Materials out. 3) Backpacks away. 4) Do Now SILENTLY.
Learning Goal:
IWBAT to determine whether two triangles are congruent by using the triangle congruence postulates and theorem.
Homework:
HW 3.5: Triangle Congruence Worksheet
Do Now:
Complete each congruence statement by naming the corresponding angle or side.
Students take out Do Now sheets.
Remind students to take out homework to be checked, copy new homework assignment in their agenda, and copy down learning goal BEFORE beginning the Do Now problem.
Take roll first, then go around and check homework as students are working.

2. Agenda: Do Now (15 min) Exploring Triangle Congruence (20 min)
SSS and SAS Congruence (15 min)
Triangle Congruence Whiteboard (10 min)
ASA and AAS Congruence (10 min)
Closure (5 min)
Triangle Theorems Quiz (30 min)

3. Exploring SSS Congruence
p. 211 in textbook. Inform students that we will use straws instead of pencils. They will mark the vertices formed by the straws by drawing a point with their pencil.

4. Exploring SAS Congruence

5. Draw Conclusions
What did you notice about the triangles you made with the three straws?
What did you notice about the triangles you made with two straws and a 45° angle between them?
If you know that two sides of a triangle are congruent to two sides of another triangle, what other information do you need to tell whether the triangles are congruent?
Explain the activity to the class. Activity is open notes/ open book.

6. Congruence Postulates

7. Congruence Postulates

8. Congruence Postulates
Decide whether enough information is given to prove that the triangles are congruent. If there is enough information, tell which congruence postulate you would use.
p. 211

9. Triangle Congruence Activity
Teacher will project two triangles at a time on the board.
Your task is to determine whether it is possible to prove that the two triangles are congruent. If so, then state the congruence theorem you would use to prove it.
1 min. independently journal, then 2 min. partner pair share per exercise.
Teacher will call on students to share and justify their responses.
Explain the activity to the class. Activity is open notes/ open book.

10. Exercise #1
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

11. Exercise #2
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

12. Exercise #3
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

13. Exercise #4
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

14. Exercise #5
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

15. Exercise #6
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

16. Congruence Postulates

17. Congruence Postulates

18. Triangle Congruence Activity
Teacher will project two triangles at a time on the board.
Your task is to determine whether it is possible to prove that the two triangles are congruent. If so, then state the congruence theorem you would use to prove it.
1 min. independently journal, then 2 min. partner pair share per exercise.
Teacher will call on students to share and justify their responses.
Explain the activity to the class. Activity is open notes/ open book.

19. Exercise #1
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

20. Exercise #2
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

21. Exercise #3
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

22. Exercise #4
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

23. Exercise #5
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

24. Exercise #6
Can you prove that the two triangles are congruent? Explain why or why not.
45 degrees

25. Other Congruence Postulates?
Angle-Angle-Angle (AAA) Congruence Postulate?
Side-Side-Angle (SSA) Congruence Postulate?
If triangles satisfy AAA or SSA, then the triangles are not necessarily congruent.

26. Triangle Congruence Whiteboard Activity
Students work in pairs. Each pair receives a whiteboard, marker, and eraser.
Teacher will present practice exercises about the congruence of triangles on the board.
Your teams have 1 minute to solve the problem and write the answer on the whiteboard with its justification.
Display your whiteboard when the timer runs out.
Explain the activity to the class. Activity is open notes/ open book.

27. Exercise #1
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

28. Exercise #2
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

29. Exercise #3
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

30. Exercise #4
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

31. Exercise #5
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

32. Exercise #6
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

33. Exercise #7
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

34. Exercise #8
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

35. Exercise #9
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

36. Exercise #10
State if the two triangles are congruent? If they are, justify your answer with a congruence postulate or theorem.
45 degrees

37. Closure
Take a moment to response to the following prompt in your notes. Please include a drawing along with an explanation.
If three angles of a triangle are the same as three angles of another triangle, are both triangles congruent?
The triangles are congruent because ____________________ .
The triangles are NOT congruent because _______________ .
109 degrees