This experiment helps students understand that ultraviolet (UV) radiation is present in natural outdoor light and that the intensity of the light varies with season and time of day. After completing this activity, students will be able to demonstrate that UV radiation can be blocked or filtered by various substances. The page contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, suggested extensions, assessment ideas, modifications for alternative learners, special notes, and an example lab report format.