Introduction: This experiment relies on the proper use of linear measurement. An accurate linear measurement relies on the proper usage of a metric ruler. Because the experiment used measurements of a curved surface, a string was used to translate the curved length into a linear measurement. All measurements were in centimeters, which is a derivative of a meter and the standard SI unit of length. The metric system, which was used here, dates back to 1585 when the use of a decimal based measurement system was suggested (1).
             Objective: Demonstrating the relationship between circumference and diameter
             Materials: Six different sized jar lids, string, metric ruler, and graph paper
             Procedure: To measure the circumference of each object the string and metric ruler were used. The string was placed around the perimater of the object and marked where it met, then the marked string was measured using the metric ruler. This procedure showed the circumference of the object. To measure the diameter of an object the widest part was measured using the metric ruler.
             Conclusion: This experiment was a good demonstration of the relationship of the circumference to the diameter. However there were many possible sources of error in the procedure used. The string was one because it can stretch and was hard to wrap straight around the object. When measuring the diameter the measurements may not have been accurate due to the way the metric ruler was used. It was hard to place at the widest part of the object and also the measurement may have been read incorrectly due to parralax when looking at the markings on the ruler.
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