This is a laboratory exercise that allows students to make their own measurements to investigate a model. Students may have studied the differential equation of motion or they may have calculated the period of oscillation by integrating $\frac{dx}{v(x)}$ (as we do in our course). They might have considered a restoring force linear in angular displacement, or the correct force that varies as sin(theta). They may simply be observing without having considered any model. In any approach, this lab gives the students the opportunity to test and refine their model, or to define the important features that any proposed model should have. The measurements are simple, and students find the mechanical system a useful, “concrete” example to refer to later in the course when oscillations of electrical circuits are studied. The latter seem to be much less “concrete” to many students.