Circumference of a Circle
Boyadzhiev, I. (Irina) (2013-04)
This applet can be used for introducing circumference of a circle. The students can create circles with different diameters by dragging the blue point D vertically. The circle can be rolled along the x-axis by dragging the green point - the center of the circle. This will “peel off” the red outer layer and transfer it to the x-axis. When the circle is rolled to the end and the entire red line is transferred to the x axis, a slider appears. Dragging the slider the students will see that the diameter fits a little more than three times in the circumference. They can record the diameter and the corresponding circumference in the spreadsheet and calculate the ratio circumference/diameter.
University of Cambridge