If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.


8 videos
4 skills
What is an angle and how do we label, measure and construct them? Great question. Luckily we have all your answers! To begin our journey towards understanding angles, we'll learn terms like vertex, acute, obtuse, circle arc, circumference, and protractor. These basic angle concepts will get you on the road to angle domination! Common Core Standards: 4.MD.C.5, 4.MD.C.5a, 4.MD.C.5b, 4.MD.C.6, 4.MD.C.7, 4.G.A.1

Angle basics

VIDEO 6:49 minutes
The naming of an angle is related to the line segments that create it. We'll also learn about the angle's vertex. Come on. Let's do this.

Naming angles exercise example

VIDEO 1:11 minutes
Here's an example exercise in which we find the correct angle name(s).

Naming angles


Angle measurement and circle arcs

VIDEO 7:37 minutes
Did you know that the measurement of an angle is realted to the arc of a circle? Yes, indeed! Watch.

Angles and circumference

VIDEO 1:40 minutes
We're slowly starting to put things together in this example exercise: angle, circle, circumference, and fractions. Woohoo!

Understanding angles


Measuring angles in degrees

VIDEO 8:22 minutes
Let's come up with an exact way to measure an angle using a protractor. We'll also lean about acute angles. Not to be confused with augly angles :)

Measuring angles using a protractor

VIDEO 3:25 minutes
Let's use our virtual protractor to measure some angles together, shall we?

More angle measurements using a protractor

VIDEO 4:05 minutes
We're practicing measuring angles using the virtual protractor. Do this a few times with us and you'll use a real protractor like a pro!

Measuring angles


Constructing angles

VIDEO 2:41 minutes
As opposed to measuring an angle using a protractor, in this example we're constructing an angle. Same idea here, just a slightly different application. You got this.

Drawing angles