# 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.
Need extra help for EL students? Try the Describing Angles pre-lesson.
##### 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.

#### Introduction

(5 minutes)
• 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.