Before measuring an angle you should always estimate the size of the angle. Initially you should think about the type of angle:

  • ACUTE LESS THAN 90°
  • RIGHT ANGLE 90°
  • OBTUSE BETWEEN 90° AND 180°
  • STRAIGHT 180°
  • REFLEX GREATER THAN 180°.
  • FULL TURN 360°.

Having recognised the type of angle you then have a range from which to make your estimate. The estimate should help you decide which scale to use, on the protractor. It may also help to think whether you are measuring in a CLOCKWISE or ANTICLOCKWISE direction. Another good trick is to count round from zero.

To measure a reflex angle you will have to measure the acute (or obtuse)angle and subtract from 360°.