Caption: Standard protractor.

Features:

1. A protractor is a divided circle used for measuring angles.

2. To make a measurement of the angle between TWO POINTS, put the protractor center of rays at the vertex of the angle you wish to measure.

   Then that angle is outlined by two rays that radiate from the vertex and go through the TWO POINTS.

   The count of angular degrees between the two rays is the angle measurement itself.

3. A bit of jargon:
   The angle subtends the circular arc between the two rays along the perimeter of the protractor which circular arc in turn subtends the angle. Got that?

4. The following Protractor videos might help too in learning how to use a protractor.

   Protractor videos (i.e., Protractor videos):

   1. Mr. v teaching Math - Geometry Lesson 1f How to use a Protractor | 2:35: Best protractor video ever!!!