1. Angles Student Expectations: 6 th Grade: 6.3.6A Use angle measurements to classify angles as acute, obtuse, or right. 7 th Grade: 7.3.6A Use angle measurements to classify pairs of angles as complementary or supplementary.

2. How do you Classify Angles? Angles are classified according to their measurement. Angles are measured in degrees. The symbol ° stands for degrees. You can write the measure of an angle using notation such as m T = 40°. The equation m T = 40° is read as “the measure of angle T equals 40 degrees.” If two angles have an equal measure, they are congruent. For example, if m R = 40° and m S =40°, then R is congruent to S.

3. Classify Angles TypeAngleDescription Acute ● An acute angle measures more than 0° but less than 90°. Right ● A right angle measures exactly 90°. Right angles are formed by perpendicular lines. Obtuse ● An obtuse angle measures more than 90° but less than 180°. Straight ● A straight angle measures 180°. Straight angles are formed by rays that lie on a line.

4. Classify Angle Pairs TypeAngle PairDescription Complementary ● Two angles are complementary if the sum of their measures is 90°. Supplementary ● Two angles are supplementary if the sum of their measures is 180°.

5. What do we use to help us? A protractor Here is a standard protractor like you use in the classroom.

6. When we use a protractor, we need to line it up correctly. You need to make sure the protractor is lined up correctly. Is this ready to measure the angle?

7. Were you right......................it wasn’t Look for the upside down ‘T’ in the middle of the straight line on your protractor. This needs to be exactly on the vertex of your angle.

8. We need to remember..... It doesn’t matter which way round the angle is, you ALWAYS need to line the upside down ‘T’ to the vertex of the angle.

9. Now you are ready. Read from the 0°, and follow the inner set of numbers.

10. Once you reach 30° you need to be careful!!! You then need to look at the 1° markings on the outer set of numbers.

11. What does it measure? This angle measures 35°.