Discovering the Formulas for Circumference and Area of a Circle

Find formulas using direct measurements and reconstruction. Groups use diagrams of circles and measure their circumferences. With several examples, classmates determine the constant of variation, pi. Pupils continue exploring circle formulas by cutting up a circle and creating a parallelogram to find the area.

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CCSS: Designed
Instructional Ideas

  • Create another circle with more wedges to use to form the parallelogram
Classroom Considerations

  • The class will already know the formulas; the takeaway from the lesson is showing the formulas are correct
  • Requires a method to measure the circumference
Pros

  • Provides templates of circles to use with the lesson
  • Contains individual teacher points for each lesson activity
Cons

  • None
Common Core