Special angle pairs

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SWBAT identify special angle pairs and determine angle measurements.

Big Idea

Set the foundation for logical reasoning by providing basic proofs of theorems about complementary, supplementary, and vertical angles.

Warm Up

10 minutes

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.

In today's warm-up, because it is the first lesson of a new unit, I review the Homework instead to maximize time in introducing a new concept.  The HW on a unit assessment day is generally spiraled review of previous topics, so it is a nice review of older material that improves retention over the course of the year.

Play of the Day

40 minutes


10 minutes

For the huddle for this lesson, I really like to go over Silver Problem 5 in detail. The primary lesson I want them to learn is the elegant logical structure that underlies the whole endeavor of geometry.   I push students to not only identify the correct answers, but the logic behind each measurement. I also make clear that there is more than one way to prove the measure of each angle... another beautiful element in math.

In this particular problem, I really stress the vocabulary to identify each angle.  Getting kids fluent in the vocabulary of, especially, congruent and supplementary, is absolutely critical as this unit develops.  I keep pushing kids until they use the correct vocabulary, and then sometimes I even do an activity where I have kids close their eyes and I say something related to the definition, and they call out the vocabulary words.

For example:

Me: Angles that sum to 180 degrees.

Students: Supplementary!

Me: Angles that are opposite of each other and congruent.

Students: Vertical!




15 minutes

HW89 Special angle pairs is to be completed at home and should take students approximately 15 minutes.