- Author:
- Amanda Muraczewski
- Subject:
- Mathematics, Geometry
- Material Type:
- Lesson Plan
- Level:
- Upper Primary
- Grade:
- 3, 4
- Tags:

- License:
- Creative Commons Attribution Non-Commercial
- Language:
- English
- Media Formats:
- Text/HTML, Video

# Education Standards

# Math Antics: What Are The Types of Angles?

# The Four Types of Angles Practice

# Visual Learning: DK Find Out! Angles

# Introduction to Angles

## Overview

The lesson starts with a review of basic geometric terms.

Angles are defined.

There are four types of angles.

A __right angle__ measures 90° and forms a square corner. If you were to sit inside a right angle, you would be sitting straight up.

An __acute angle__ measures less than 90° and is open less than a right angle. Acute angles have a smaller measurement. Think of them as small and cute. =) If you were sitting inside an acute angle, you would be bent together like a 'V'.

An __obtuse angle__ measures more than 90° and is open more than a right angle. Obtuse angles have a larger measurement. If you were to sit inside a obtuse angle, you would be leaning back as if you were lounging in a beach chair by the pool.

A __straight angle__ measures exactly 180° and forms a straight line. If you were to sit inside a straight angle, you would actually have to lay down flat on your back.

# Points, Lines, Rays

The first task involves vocabulary for review of basic geometric terms.

Let's review some of our basic geometric terms.

A __point__ is an exact location in space.

A __line __is a straight path of points that goes on and on in opposite directions.

A __line segment __is a piece of a line with two endpoints.

A__ ray__ is a part of line that has one endpoint and continues on and on in one direction. Think of "One Way Ray".

# Angles

Introduction to Angles

Now, we are going to talk about angles.

Angles are formed by two rays that have the same endpoint. Angles are named with three letters. The shared endpoint is the center letter. The other letters represent points from each ray.

# The Four Types of Angles

The four types of angles are defined.

There are four types of angles.

A __right angle__ measures 90° and forms a square corner. If you were to sit inside a right angle, you would be sitting straight up.

An __acute angle__ measures less than 90° and is open less than a right angle. Acute angles have a smaller measurement. Think of them as small and cute. =) If you were sitting inside an acute angle, you would be bent together like a 'V'.

An __obtuse angle__ measures more than 90° and is open more than a right angle. Obtuse angles have a larger measurement. If you were to sit inside a obtuse angle, you would be leaning back as if you were lounging in a beach chair by the pool.

A __straight angle__ measures exactly 180° and forms a straight line. If you were to sit inside a straight angle, you would actually have to lay down flat on your back.

# Classroom Angle Search

Students will look around their classroom environment and identify the various types of angles.

Take a moment to look around the classroom.

Can you find three different examples right angles? Where?

Are there any obtuse angles? Any acute?

Can you find five different straight angles?