Melanoma, a type of cancer that develops in melanocytes, is usually caused by direct exposure of skin to ultraviolet (UV) radiation resulting in cellular damage. In this study, a procedure to determine the effects of various commercial sunscreens with SPF values ranging from 15 to 100 was developed using pig skin to mimic human skin. These sunscreens contain inorganic filters, such as zinc oxide and titanium dioxide; active organic ingredients, such as octocrylene and oxybenzone; or both. As a model for human skin, pig skin was analyzed before and after UV exposure, and the presence of free radicals was measured using electron paramagnetic resonance (EPR) spectroscopy. Using this method, students were able to quantify radical formation following irradiation and use this as a basis to compare the efficacies of sunscreens against UVA. This experiment allowed undergraduate students to characterize a complex chemical process (light-induced radical formation) and relate it to something they experience every day (sun damage). Interestingly, students found higher levels of postillumination radical formation in sunscreen-treated samples, perhaps indicating sunscreen-induced stabilization of these species. Student outcomes included learning how to collect and interpret EPR data, statistical analysis of these data, and the preparation of reproducible biological samples. Students also consulted literature sources to properly display their measurements.