`Circles - Diameter, Circumference, Radius and the Discovery of PiKathleen Ryan                  Randolph Magnet School                               7316 S. Hoyne                               Chicago IL 60636                               (773) 535-9015Objective:This seventh grade math lesson is designed to help students identify andmeasure the diameter, circumference, and radius of a circle.The students should discover the approximate value of pi through therelationship between the diameter and circumference.Materials Needed:Various size circles, meter sticks, metric tape measures, rulers, scissorsScotch tape, drywall tape, calculators, and table worksheet.Strategy:1.  Identify the diameter, circumference, and radius of a circle.2.  Demonstrate for the students how to measure the diameter and circumference    on a circle.  Explain that radius is half of the diameter.3.  Six various size circles are labeled A-F.  Include many samples of the same    size circles.4.  Working in pairs or in groups have the students record the diameter and    radius of each circle using a ruler, tape measure, or meter stick using    centimeters.  This information is recorded on a table worksheet. 5.  The students then measure the circumference using drywall tape.  The    drywall tape is placed around the perimeter of the circle and marked with a     pencil and then cut.  The drywall tape is then measured on a ruler,     tape measure, or meter stick.  The circumference is recorded on the table     worksheet.                                      6.  After the students have recorded the information for circles A-F, ask the    students if they see a relationship between the diameter and circumference.7.  Divide the circumference by the diameter for each circle.8.  Discuss the results of circumference divided by diameter.9.  Compare the class' results with the standard value of pi(3.14159265...).    Write the symbol for pi (p) on the chalkboard.                             Performance Assessment:  The students will measure the diameter of a record album or another circularobject (other than the previously used circles) and predict the circumference.The students will then measure the circumference of another circular object andpredict the diameter.Conclusion:The students should have a clear understanding of the relationship between circumference and diameter and be able to apply this knowledge to similar situations.    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