Unit 5, Investigating Chance, brings together all of the concepts from Units 1-4 to investigate chance. Students work with hand-held spinners and with TinkerPlots to explore the behavior of 2-color spinners. The purpose is to develop understanding of probability as a measure of uncertainty.The key idea is that the outcome of any single repetition cannot be known in advance,but with many repetitions, the uncertainty of particular outcomes can be measured.Students examine two complementary approaches to estimating probability, theoretical and empirical.They explore the probability of joint, independent outcomes, such as the sums of the outcomes of two spinners, from theseperspectives. The unit includes explorations of empirical approximations to the sampling distribution of one or more statistics, in light of changes in number of repetitions of a process (the sample size is the number of repetitions). The sampling distribution is the cornerstone of statistical inference. The Chance (Cha) and Conceptions of Statistics (CoS) constructs describe benchmarksof conceptual progress about probability and about the sampling distribution of a statistic.