Angles Teaching Resources

Explore angles worksheets, hands-on activities, games and more resources created by teachers for your lesson plans!

This collection of math resources for elementary and middle school teachers is aligned with both TEKS and the Common Core Curriculum, and it's been stocked with everything you will need to teach students how to identify the different types of angles, measure real-life examples, determine the measure of an unknown angle and more!

Lay the groundwork for your students' understanding of geometry and spatial relationships with resources that have undergone a careful review by the math teachers on the Teach Starter team to ensure they're ready for your lesson plans and your students!

New to teaching this portion of the math curriculum? Or maybe you're just looking for fresh ways to engage your students on the topic? Read on for a primer from our teacher team, including a kid-friendly definition and a look at different types of angles and angle pairs from right to acute, complementary to adjacent and so on.

What Are Angles? A Kid-Friendly Definition

If you're introducing angles for the first time, it can be helpful to have a kid-friendly definition on hand to start the lesson. Here's one that our teacher team likes to use!

Shapes are made up of lines and corners, or what we call vertices. Angles are the measure of those corners or vertex points.

What Are the Different Types of Angles and Their Functions?

Depending on the grade level you're teaching, we know the types of angles you will be talking about in your classroom will likely differ. That said, here's a quick reminder of the various types of angles, along with a look at their functions, to use as a refresher.

1. Right Angle

Right angles measure exactly 90 degrees and look like the corners of a square. They're found in shapes such as squares and rectangles, and they're typically the first angle kids learn about in elementary school.

Right angles create stability in structures and ensure that objects fit together properly. They also help determine directions, so they play into map skills and navigation.

2. Acute Angle

An acute angle is one that measures less than 90 degrees but more than 0 degrees. Found all around us — from the corners in triangles to the hands of the classroom clock when it shows a time earlier than 3:00 — acute angles appear in designs and constructions anywhere a sharp or narrow corner is needed.

These angles are typically used to describe relationships in triangles and other geometric shapes.

3. Obtuse Angle

An obtuse angle measures more than 90 degrees but less than 180 degrees. This angle type can also be spotted in the classroom clock hands, but it appears when the time is after 3:00. Obtuse angles are also found in the shapes of many irregular polygons.

Text reads Obtuse angle greater than 90 degrees less than 180 degrees. There's also an obtuse angle example illustration

Obtuse angles can describe the bending or opening of objects, and they're used in design to create open space.

4. Straight Angle

Students are often surprised to find out that a straight line is a type of angle! Named a "straight angle," it measures exactly 180 degrees.

Understanding straight angles is fundamental to understanding the relationships between lines and their directions.

Text reading straight angle exact 180 degrees appears beneath an illustration of a straight angle

5. Reflex Angle

When you have an angle that measures more than 180 degrees but less than 360 degrees, it's called a reflex angle.

Reflex angles often appear in situations where bending or curving is important.

Types of Angle Pairs

In addition to the types of individual angles, there are also a host of angle pairs that have a special relationship with one another.

1. Adjacent Angles

When you have two angles that share a common vertex and a common side but do not overlap, they're known as adjacent angles.

2. Vertical Angles

Vertical angles are pairs of angles that are opposite when two lines intersect. They are always congruent, which means they have the same measure.

Middle school students who are ready to learn about the properties of angles formed by intersecting lines tend to start by learning about this angle type.

They'll find these angle pairs in the letter X and at some street intersections. Learning about them will form the basis for understanding angles formed by transversals.

3. Complementary Angles

When a pair of angles add up to 90 degrees, they're called complementary angles. These types of angles can be adjacent or non-adjacent.

These angles can also be found right in the classroom on your clock. They're the angles created between the minute and hour hands of a clock when they add up to 90 degrees.

4. Supplementary Angles

Supplementary angles combine to form a straight line. This angle pair represents two angles that add up to 180 degrees when put together.

Two sets of right angles can be supplementary as their sum is 180 degrees (90 + 90 =180), and a set of obtuse and acute angles can also be supplementary.

5. Corresponding Angles

Corresponding angles are in the same relative position on the two parallel lines and the transversal. They have equal measures.

Corresponding angles are found when a transversal intersects two parallel lines, such as in a fence or many different architectural structures.

6. Alternate Interior Angles

Angles that are on opposite sides of the transversal and inside the parallel lines are called alternate interior angles. They have equal measures.

7. Alternate Exterior Angles

Angles found on opposite sides of the transversal and outside the parallel lines are known as alternate exterior angles. Like alternate interior angles, these also have equal measures.

Like corresponding angles, alternate interior angles and alternate exterior angles can both be found when a transversal intersects two parallel lines.