Although studies in a variety of settings suggest that participant reactions to the research context can threaten the validity and generalizability of study findings, there have been almost no investigations of participant reactivity in museums. In this experimental study, the authors compared the behaviors and learning outcomes of visitors at two versions of an interactive mathematics exhibit who had either been actively recruited by a data collector or passively recruited using posted signage. They assessed the amount of time visitors spent at the exhibit, the number of mathematical exhibit