Susan Chaffee
Geometry Section 3.2 Spring 2009
Lesson 1 – Section 3.4
Unit: Chapter 3 Parallel and Perpendicular Lines
Lesson: Section 3.4
Goals: To classify triangles and find measure of angle using triangle angle-sum and exterior angles.
Lesson Objectives:
Enduring Understanding:
Materials and/or Special Notes:
Lecture materials (computer):
Prior Knowledge:
Write on the board:
Section 3.4…Parallel Lines and the triangle angle-sum theorem
Motivation:
Review:
Lesson Activites :
1)
Student activity. Draw a triangle on your paper. Measure each angle. Add them and what do you
notice.
2)
SB 1: Triangle sum theorem.
a.
3)
SB 2: Triangle types
a.
4)
Work exercises 1-5.
Work exercises 6-7
Define exterior angle of a polygon. Angle formed by one side and an extension of the adjacent side.
a.
Student activity. Use triangle cutout to place angles 2 and 3 next to 1. What is the sum of
1,2,3 ?
b.
Show algebraically. Angle2 + angle 3 = 180 – angle 1. If we call the outside angle 4. Then
angle 4 = 180 – angle 1.
5)
Worksheet: #12-15