Measuring Angles: Lesson for Kids

Instructor: Lisa Hanson

Lisa is a Continuous Improvement Coach for her school district and has taught in elementary school for many years. She has a master's degree in curriculum and instruction.

Get ready to wrangle up some angles! We can find angles everywhere. In this lesson, you will learn about types of angles and how to measure them with a protractor.

What is an Angle?

There are angles all around us! We see them in shapes, on furniture, walls, floors, and even on playgrounds.

An angle is formed by two rays connected by a point, or vertex.

Angle Showing the Vertex
angle with vertex

When we want to measure an angle, we measure the space between the two rays. This is measured in degrees. These are not the same kind of degrees you hear about when the weather is cold or hot. We use a special tool called a protractor to measure angles.

A protractor is a tool used to measure angles.

Types of Angles

Right Angle

A right angle has a measurement of 90 degrees, which is written 90°. This means that one side is perfectly flat, or horizontal, and the other is going straight up and down, or vertical. You can see an example in the picture below. You see this type of angle all over the place, especially on things that are rectangular or square in shape. We compare all angles to a right angle to see if the space between the rays is bigger or smaller than 90°.

These are examples of acute and right angles. Acute angles are smaller than right angles.
right and acute angles

Acute Angle

The space between the two sides of an acute angle is always less than the right angle. This means that an acute angle is less than 90°. It can measure anywhere from 0-89°. You can see an example in the picture. If you look at a triangle, at least two of the corners are always acute angles. A way to remember the name is to think of an acute angle as a 'cute' angle because it is smaller.

Obtuse Angle

The space between the two sides of an obtuse angle is always bigger than the right angle. So, an obtuse angle is larger than 90°. It can measure anywhere from 91-179°. See the picture below for an example. The obtuse angle is thought to be a 'fat' angle.

An obtuse angle is larger than a right angle.
Obtuse Angle

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