Learn Radian Measure of Special Angles

This Learn Radian Measure of Special Angles video also includes:

While many classes memorize the radian and degree relationships for special angles in the unit circle, this presentation is uniquely grounded in the "why's" behind these common angles. With an emphasis on the geometric interpretation of an angle as a sector of a circle, the radian measures for angles in the first quadrant are carefully developed. Skills in adding and subtracting unit fractions are then used, resulting in the iconic labeled unit circle with common angle measures. Common mistakes, such as mistaking pi radians for a circle measure instead of a semicircle, are teased out and a point made of the ability to develop the angle measures from basic principles instead of just rote memorization. 

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CCSS: Designed
Instructional Ideas

  • Consider providing blank unit circles and protractors for the class to create their own reference sheets for special angles
  • Excellent introduction to special angles for viewing outside of class in the flipped classroom model
  • After developing the reasoning behind the importance of special angles, use speed drills or competition-style games to develop familiarity with the patterns of special angles
Classroom Considerations

  • May need to prepare remediation for learners in adding and subtracting fractions without converting to decimals
  • Lesson requires creation of a free LearnZillion account for access
  • Video presentation is done in Adobe Flash, check for needed Internet access or computer updates prior to class
  • Slides from video presentation available for note taking under the Additional Materials tab in LearnZillion

  • Math facts developed from basic circle properties, instead of presented without context for memorization
  • Easily understood and pleasant-voiced narrator
  • Several examples and common mistakes detailed throughout presentation

  • No practice problems for class or homework available
  • No blank unit circle for labeling provided
Common Core