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Sunday, May 25, 2014

Circles Craft

How can a stack of paper plates make reviewing circles more fun? I gave each student a paper plate and displayed these definitions on the board:
  • center - middle of circle
  • radius - line segment from center to side
  • diameter - line segment from side to side through center
  • cord - line segment from side to side not through center
  • circumference - distance around

When they finished labeling, we used the other side to display measurement of the paper plate. (The plate was just over nine inches; we rounded this number to make it easier for fourth graders to handle.) From the diameter, they were able to calculate the radius, and they were excited because I "let them" use formulas, calculators, and the almighty pi to compute area and circumference. I displayed the formulas, and away they went!
  • d = 2r
  • C = π d  or  C = 2 π r
  • A = π r 2