An angle measurement is the number of degrees (out of 360) in the angle's arc. To reinforce this concept, draw a full circle and then, using a ruler, draw several radii. Measure the angles created by the radii with a protractor. Mark the angle measurements at the arc created by the angle. Add the arc measurements to sum 360 degrees.
To gauge the accuracy of an angle measurement, it helps to estimate the angle. Practice estimating angles using the vocabulary terms that relate to angles. Have each student prepare four index cards. Each index card should bear one of the following terms: right, acute, obtuse and line. Draw angles on the blackboard, one at a time. Instruct students to hold up the index card that correspond with the angles drawn.
Practice measuring angles with a protractor. Using a ruler, draw 10 angles of different degrees on paper. Estimate the angles using the right angle (90 degrees) and the straight line (180 degrees) as mental references. Then measure the angle with a protractor, aligning one of the angle sides to the line of the protractor. Note and record the difference between the correct measure and your estimate.
Practice the concepts of angles and measurements with a fun, partner activity. Pair up with another student. Hiding your paper from your partner, draw an angle on a piece of graph paper using the edge of a protractor. Measure the angle with the protractor. Instruct your partner to draw the angle by giving him the points (x and y coordinates) of the endpoint of the angle and the points at which each angle side ends. Instruct your partner to measure the angle to confirm he drew it correctly. Compare the two drawings and then switch roles.