How to Measure Angles on a Circle

Have you ever been on a Ferris wheel?

To measure how many turns a Ferris wheel has done, we can measure the angle of the turn.

Full Turn

When a Ferris wheel makes 1 full turn, we call that a 360° turn.

Doing a full turn brings you back to where you started.

3/4 of a Full Turn

A Ferris wheel can also make 3/4 of a full turn.

      3/4 of a full turn makes a 270° angle.

1/2 of a Full Turn

A Ferris wheel can also make 1/2 of a full turn.

      Half of a full turn makes a 180° angle, or a straight angle.

1/4 of a Full Turn

A Ferris wheel can also make 1/4 of a full turn.

      A 1/4 turn makes a 90° angle, also called a right angle. 

It cuts out 1/4 of a circle.

Tip: If you make four 90° turns, you'll make a full 360° turn, and end up where you started.

1/8 of a Full Turn

Here's what 1/8 of a full turn looks like.

What type of angle is it?

Very good. An acute angle.

1/8 of a turn forms an angle that's 45°.

That's half of a right angle.

Angles and Fractions

      Fractions, just like angles, can describe how much you turn an object.

A 90° angle turns an object 1/4 of the way around.

A 180° angle turns it halfway around. It makes 1/2 of a circle.

A 270° angle makes 3/4 of a circle.

90°, 180°, and 270° angles are called benchmark angles.

They divide a circle into right angles that are easy to think about.

Great job learning about angles in a circle.

Now, try the practice to help you remember for longer.