Large numbers permeate political life; students of political science can expect to encounter a wide range of numbers in newspaper articles, course readings, and statistics. Recent research in cognitive psychology has demonstrated that American adults make systematic errors when comparing numbers in the millions, billions, and trillions. Political decisions made by voters often require weighing large quantities that range across many orders of magnitude, which is difficult without at least a basic understanding of relative magnitudes. If students also lack an understanding of large numbers, professors cannot meaningfully teach students about political phenomena involving such magnitudes. Therefore, we designed and tested an exercise to improve students' accuracy in dealing with large magnitudes, which had immediate and sustained effects both on their abilities to accurately work with large numbers and their perceptions of numbers in political judgments. (Benhabib, 2012) American citizens are often called upon to make political judgments that require familiarity with large numbers, yet studies find that people make systematic errors in the estimation of large magnitudes. The failure of American citizens to engage with large numbers in a critical manner, especially numbers used in policy discussions and news media, is a serious impediment to meaningful public discussions about a wide range of policy issues and political matters (Best 2012; Blastland and Dilnot 2007;Maier and Imazeki 2012;Huff 1993). An accurate understanding of large magnitudes not only reinforces better citizenship, but also prepares students for content that is commonly encountered in political science courses, such as budget politics, migrant populations, and climate change statistics. Without a proper facility with these numbers, it is hard to imagine students could contribute substantively to discussions of current events or the basic political phenomena that involve interactions across scales, such as population change, emissions levels, or the national budget (Payne and Williams 2011;Andersen and Harsell 2005). Even outside of political science, there has been increased attention paid to the effect of numeracy on decision-making, personal health choices, and future employment opportunities for students (Peters et al. 2006;Ward et al. 2011). Still, surprisingly little literature exists on best practices for teaching number evaluation strategies to students in the classroom, or for integrating these practices across the political science curriculum. A rich pedagogical literature on teaching research methods attests to the trepidation that students feel about encountering numbers in formal ways in political science Using Kolb's Experiential Learning Theory, we designed an exercise that provides a concrete experience to serve as the starting point for reflection, conceptualized thinking, and experimentation. By training students to think about large magnitudes more accurately, the exercise also influences students' perceptions of polit...