Doing the Moon Dance

We gave each student a small ball on a stick (golf ball or ping pong ball) to represent the moon. We turned out the classroom lights and used a lamp to represent the sun. First, everyone held their ball so that it was eclipsing the lamp. I asked, “What is the angle between your arm when pointing one arm at the lamp and holding the ball in the new 'moon' position?” 0 degrees.
As we moved through the moon phases, the students observed the angle relationship created by the “sun” and “moon”:

• New = 0 degrees
  
• Waxing Crescent = 0 - 90 degrees
  
• First Quarter = 90 degrees
  
• Waxing Gibbous = 90 - 180 degrees
  
• Full = 180 degrees
  
• Waning Gibbous = 180 - 90 degrees
  
• Third Quarter = 90 degrees
  
• Waning Crescent = 90 - 0 degrees

We used the term acute, right, obtuse, and straight to describe the angles formed.