# ALEX Lesson Plan

## Angles, Angles, and More Angles

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This lesson provided by:
 Author: Morgan Boyd Organization: Retirement
General Lesson Information
 Lesson Plan ID: 35590 Title: Angles, Angles, and More Angles Overview/Annotation: This lesson is designed to develop knowledge about the angles of a triangle. This lesson will prove that the interior angles of a triangle will have a sum of 180 degrees. This lesson will prove that an exterior angle is the sum of the remote interior angles. This lesson will show the relationships of the angles of parallel lines and transversals.This lesson results from the ALEX Resource Gap Project.
Associated Standards and Objectives
Content Standard(s):
 Mathematics MA2019 (2019) Grade: 8 25. Analyze and apply properties of parallel lines cut by a transversal to determine missing angle measures. a. Use informal arguments to establish that the sum of the interior angles of a triangle is 180 degrees. Unpacked Content Evidence Of Student Attainment:Students: Find missing angles when presented angles formed by a transversal cutting through parallel lines. Write equations to find missing angles when an angle is represented by a variable expression. Prove that all triangles have an interior angle sum of 180 degrees by using given angle relationships that form a triangle.Teacher Vocabulary:Transversal Corresponding Angles Vertical Angles Alternate Interior Angles Alternate Interior Angles Supplementary AdjacentKnowledge:Students know: That a straight angle is 180 degrees That a triangle has three interior angles whose sum is 180 degrees. The definition of transversal. How to write and solve two-step equations.Skills:Students are able to: Make conjectures about the relationships and measurements of the angles created when two parallel lines are cut by a transversal. Informally prove that the sum of any triangle's interior angles will have the same measure as a straight angle. Understanding:Students understand that: Missing angle measurements can be found when given just one angle measurement along a transversal cutting through parallel lines. Every exterior angle is supplementary to its adjacent interior angle. Parallel lines cut by a transversal will yield specific angle relationships that are connected to the concepts of rigid transformations (i.e. vertical angles are reflections over a point. corresponding angles can be viewed as translations). The sum of the interior angles of a triangle is 180 degrees.Diverse Learning Needs: Essential Skills:Learning Objectives: M.8.25.1: Define exterior angles, interior angles, vertical angles, adjacent angles, alternate interior angles, alternate exterior angles, corresponding angles, and transversal. M.8.25.2: Identify attributes of triangles. M.8.25.3: Identify exterior angles, interior angles, vertical angles, adjacent angles, alternate interior angles, alternate exterior angles, and corresponding angles. M.8.25.4: Identify a transversal. M.8.25.5: Apply properties to find missing angle measures. M.8.25.6: Discover the Angle Sum Theorem (sum of the interior angles of a triangle equal 180 degrees). Prior Knowledge Skills:Define supplementary angles, complementary angles, vertical angles, adjacent angles, parallel lines, perpendicular lines, and intersecting lines. Discuss strategies for solving mulit-step problems and equations. Identify all types of angles. Identify right angles and straight angles. Alabama Alternate Achievement Standards AAS Standard: M.AAS.8.25 Compare any angle to a right angle using greater than, less than, or congruent to the right angle.

Local/National Standards:

Primary Learning Objective(s):

The student will be able to explain the sum of the angles in a triangle equals 180 degrees.

The student will be able to calculate the measure of an exterior angle of a triangle.

The student will be able to calculate the measure of an interior angle when given the exterior and remote interior angle.