[size=150]Measure the circumference of the circle by unrolling it into a straight line. Explore the relationship between the circumference and the diameter of the circle.[br][br][list=1][*]Drag the center of the circle to unroll it. Change the diameter using the point on the circle.[br][/*][*]Drag the slider to find out how many times the diameter fits in the circumference.[/*][/list][/size]