Purpose:Show the relationship between the diameter and the circumference of a circle
Description:A chain, originally wound around a cylinder, is unwound. The diameter of the cylinder can be compared with the length of the chain wound off one turn, so the value of pi may be approximated. This is valuable to introduce students to the concept of radians, a unit common in physics formulae but rarely encountered in daily use.
This can also be used to introduce concepts related to estimation and dimensionality. Encourage students to make predictions about the relationships of the lengths, then try them out hands-on so they can test and analyze their predictions.