This paper reports on a simple hands-on laboratory procedure for high school students in studying both radiation damage and DNA repair systems in bacteria. The sensitivity to ultra-violet (UV) radiation of both "Escherichia coli" and "Serratia marcescens" is tested by radiating them for varying time periods. Two growth temperatures are used in order to induce the production of the melanin-like pigment prodigiosin in "Serratia marcescens." Several explanations are then suggested for the differences observed, including cellular DNA repair systems and the presence of the intracellular pigment prodigiosin. The experiment's results prove that the different sensitivities to radiation of both bacterial strains are caused by cellular DNA repair systems, and not by other cellular molecules, such as the pigment prodigiosin. The paper also suggests further laboratory investigations designed to enhance high school students' understanding of bacterial DNA repair systems. (Contains 2 figures.)