4.4 Congruent Triangles
Triangle Sums
I.SectionObjectives
- Identify interior and exterior angles in a triangle.
- Understand and apply the Triangle Sum Theorem.
- Utilize the complementary relationship of acute angles in a right triangle.
- Identify the relationship of the exterior angles in a triangle.
II.MultipleIntelligences
- Begin this lesson by talking about interior and exterior angles of a triangle. Request that students draw an
example in their notebooks of a triangle with interior and exterior angles. - Request that they label the interior angles red and the exterior angles in blue.
- Move on to the Triangle Sum Theorem.
- Remind students that this is information that they already know, but that it has now been written as a theorem.
- One way to make this part of the lesson interactive is to draw a diagram of a triangle on the board and to play
“fill in the blank” with the students. You can even have them work on teams and see which team can complete
the addition the quickest. - Another fun way to do this is to use only mental math. This is great for students to practice their thinking
skills. The big thing to watch for is students calling out- remind them to raise a hand when done or to stand
up. - If you wish to keep this more traditional, then have students draw the triangles at their seats but use a protractor
to measure angles and solve for missing angles.
III.SpecialNeeds/Modifications
- Review the following terms.
- Interior angles
- Triangle
- Exterior angles
- Write new theorems on the board.
- Request that students copy this information down in their notebooks.
- Allow time for questions to check on student understanding.
IV.AlternativeAssessment
- The best way to assess this lesson is through observation.
- If you are playing the game, observe which students are actively participating and which ones aren’t.
- If completing seat work, walk around and check in with students as they work. Answer questions and offer
assistance as needed.
4.4. Congruent Triangles