A laboratory experiment currently used in an undergraduate physical chemistry lab to investigate the rates of crystallization of a polymer is described. Specifically, the radial growth rates of typical disc-shaped crystals, called spherulites, growing between microscope glass slides are measured and the data are treated according to polymer crystallization theory. The polymer used is a commercially available poly(ethylene glycol). Effects of molecular weight and crystallization temperature on the growth rate are demonstrated. Background information for students and instructor, experiment procedure, and full analysis of students' results are included in the Supporting Information. (Contains 5 figures.)