This document provides instructions on measuring angles using a protractor. It defines what a protractor is, the parts of a protractor, and the steps to accurately measure an angle which include placing the protractor's center mark on the angle's vertex and rotating the protractor to align one ray with the zero-edge to read the measurement of the other ray. Common mistakes like using the wrong scale or not centering on the vertex are also outlined.

1. Math 6: Geometry
Investigating Angles

2. Different types of angles
 Label degrees:

3. How to Use a Protractor
 How to carefully place and read the protractor
 Protractor = tool to measure an angle

4. Parts of a Protractor

5. Vocabulary Words

6. Measuring an Angle
 Step 1: Determine if the type of angle. Eg. Acute or obtuse
 Step 2: Place the center mark of the protractor on the vertex
of the angle
 Step 3: Rotate the Zero-edge of the protractor to line up with
one ray of the angle and for the other ray of the angle to
cross the protractor’s scale
 Step 4: Read the measure of the angle of the ray that crosses
the protractor’s scale

7. Common Mistakes
 1) Using the incorrect scale
 2) The centre mark is not on the vertex. (This usually happens
after rotating the protractor.
 3) Counting the marks in the wrong direction. Pay attention
to whether these numbers are increasing or decreasing.

8. How to Measure Angles
 Master 3.6
 Measure
angles

9. In Class Work
 pg. 84 – 85 # 1, 2, and 4

10. Homework
 pg. 34 + 35