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Lesson Materials

Protractor - Measure Angles

READ the instructions on the right and INTERACT with the GeoGebra applet below.


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Objective

6.13 The student will
a) estimate angle measures, using 45°, 90°, and 180° as referents, and use the appropriate tools to measure the given angles; and
b) measure and draw right, acute, and obtuse angles.

 Directions Close 
  1. The blue point moves the protractor.
  2. The red point rotates the protractor.
 Directions 2 Close 
  1. Use the protractor to measure the eight labeled angles.

  2. Why do you not have to measure the two unlabeled angles? What are their measures?

 Hands-On Activities Close 
Practice online measuring angles
Identify angle types
 Other Web Sites Close 
  1. CIMT
    2. Centre for Innovation in Mathematics Teaching
  2. BBC Select Angles from the list
 Puzzles & Problems tangram Close 

From Math Forum: When studying angles, we are taught that a complete rotation is 360 degrees. (90 degrees and you've turned one-quarter, 180 degrees and you've turned halfway and so on.) Why or what is the history of 360 degrees? Why not something like 500 degrees for a complete rotation? (where 125 degrees is a one-quarter turn, and so on.)