How to Measure Angles with a Protractor

Measuring angles is an important skill that you’ll learn in Year 7 Math. One of the best tools for this job is called a protractor. It’s a tool that looks like a half-circle or a full circle marked with numbers that show degrees. This helps you find out how big an angle is. Let’s go through how to use it step by step!

How to Use a Protractor: Step by Step

1. Align the Protractor: First, put the center hole of the protractor over the point where the two lines meet. This point is called the vertex of the angle.

2. Line Up the Baseline: Make sure one side of the angle lines up with the straight zero line on the protractor. This line is important for getting the right measurement.

3. Read the Scale: After you have the baseline lined up, look at the other side of the angle. Look for where it touches the number markings on the protractor. Protractors usually have two sets of numbers. One set goes from 0 to 180 degrees going one way, and the other goes from 0 to 180 degrees going the other way. Check which scale you should use based on how your angle is turned.

   • Example: If one side is on the 0° line and the other side touches the 70° mark on the upper scale, then your angle measures $70^\circ$.

4. Record the Measurement: Make sure to write down the angle measurement with the degree symbol, like this: $70^\circ$.

Tips for Getting It Right

• Use a Flat Surface: Make sure you’re working on a flat surface to see your protractor clearly.

• Check Your Alignment: If the measurement doesn’t seem right, double-check to see if the protractor and the lines are still lined up.

• Practice with Different Angles: Try measuring different types of angles! Practice with acute angles (less than $90^\circ$), right angles ($90^\circ$), and obtuse angles (between $90^\circ$ and $180^\circ$) to get better.

Visualize It

Think of the protractor like a pizza slice:

• The very tip of the pizza (the vertex) is where you place the protractor.
• The outer crust shows the degree markings.
• Each slice you cut deeper into the pizza measures the angle of that piece!

By learning how to measure angles accurately with a protractor, you’ll do great in geometry! Remember, the more you practice, the better you will get. So grab your protractor and start measuring different angles to become an angle expert!