Prove exterior angles of triangles 2
Lesson 8 of 9
Objective: SWBAT prove facts about the exterior angles of a triangle.
Each day, students complete a warm-up that usually consists of spiraling the previous day's material, in addition to older material. Warm-up problems also sometimes extend lessons that students have encountered before to more unfamiliar contexts.
For a video narrative about how I structure each lesson, and how the warm-up fits in, click here.
Play of the Day
Today is about getting more and more kids fluent in their ability to prove this fact, and so I ask a few kids to come up to the board to present proofs, and to get evaluated by their peers. We use two simple questions to evaluate:
1. Is the logic correct?
2. Is the presentation clear and understandable?
At this point, students are developing the habits of mind needed to be strong proof-writers. They establish certain facts, choose the logical and correct sequencing of each step, and make a strong conclusion based on their reasoning. We talk about these three elements as the three elements that form the basis of a strong proof.
Homework 98 is to be completed at home and should take students approximately 15 minutes.