Lesson Plan

Classifying Triangles by Internal Angles

Classifying figures by features is a fundamental geometry skill. Use this lesson plan to teach your students how to categorize triangles by internal angle types.
Download lesson plan
Need extra help for EL students? Try the Describing Angles pre-lesson.
Grade
Subject
View aligned standards
Need extra help for EL students? Try the Describing Angles pre-lesson.

Learning Objectives

Students will be able to sort triangles based on features of their internal angles.

The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.
EL adjustments

Introduction

(5 minutes)
Sorting Triangles
  • Start off with a game of Simon Says. Direct your students to imitate you making three different angles with your arms: right angle (one at 90 degrees), an acute angle (one at less than 90 degrees), and an obtuse angle (one greater than 90 degrees).
  • As you make your angle and the students imitate you, tell them the definition of each angle you make. For example, "Simon says make a right angle; this angles is at 90 degrees."

Beginning

  • Provide visuals of each of the angles with their names for ELs to model.
  • Allow them to repeat the definitions in their home language (L1) or their new language (L2).
  • Define the terms actue angle, obtuse angle and right angle and create hand motions with students' input to represent these terms.

Intermediate

  • Have students restate the definitions using some of the following math key terms: "obtuse," "acute," "right angle," "degrees," etc.