1. MEASURING ANGLES USING FULL-CIRCLE PROTRACTORS Goal: To learn how to measure angles using full-circle protractors

2. NOW LET’S REVIEW WHAT WE KNOW ABOUT ANGLES…. What are the names of the different parts of an angle?

3. HOW DO WE MEASURE ANGLES USING THE HALF-CIRCLE PROTRACTOR?

4. NOW LET’S DO SOME 180’S AND 360’S

5. WHAT IS THE DIFFERENCE BETWEEN THE HALF-CIRCLE PROTRACTOR AND THE FULL-CIRCLE PROTRACTOR?

6. AS YOU CAN SEE, THE MARKS ON THE EDGE OF THE PROTRACTOR ARE LABELED FROM 0°TO 360° IN A CLOCKWISE DIRECTION. SOMETIMES, THE ANGLES WILL HAVE ARROWS SHOWING US WHICH WAY TO MEASURE BUT SOMETIMES THEY WONT. IF THEY DO NOT, MAKE SURE YOU ARE MEASURING IN A CLOCKWISE DIRECTION.

7. NOW OPEN UP YOUR SRB BOOK TO PAGE 142. WE ARE GOING TO BE MEASURING ANGLE B USING THE FULL-CIRCLE PROTRACTORS. ONCE YOU HAVE MEASURED THE ANGLE, GIVE ME A THUMBS UP SO I KNOW YOU’VE GOT IT!

8. NOW HOW WOULD YOU MEASURE ANGLE C? ANGLE C IS WHAT WE CALL A “REFLEX ANGLE”. A REFLEX ANGLE IS MORE THAN 180° BUT LESS THAN 360°. There are two VERY important steps to follow when measuring an angle using a full-circle protractor.

9. 1.Put the center of the circle on the vertex of your angle. 2. Put zero on the starting line.

10. LET’S ALSO PRACTICE DRAWING AN ANGLE 1.Everybody take a ruler and draw a ray 2.Place the center of the full-circle protractor on the endpoint of the ray and align the 0° mark with the ray. Make a dot on the paper at the 60° mark. 3.Draw another ray from the endpoint of the fist ray to the dot. 4.Now draw an arrow to identify the direction of the rotation and use a letter to name the vertex point.