Abrahamson, D. & Wilensky, U. (2003). The quest of the bell curve: A constructionist approach to learning statistics through designing computer-based probability experiments. In M. Allessandra, C. Battanero, R. Biehler, M. Henry, & D. Pratt (Eds.), Proceedings of the Third Conference of the European Society for Research in Mathematics Education. THE QUEST OF THE BELL CURVE: A CONSTRUCTIONIST APPROACH TO LEARNING STATISTICS THROUGH DESIGNING COMPUTER-BASED PROBABILITY EXPERIMENTS Dor Abrahamson Uri Wilensky abrador@northwestern.edu uri@northwestern.edu Center for Connected Learning and Computer-Based Modeling Northwestern University This paper introduces the rationale, explains the functioning, and describes the process of developing ‘Equidistant Probability’, a NetLogo microworld that models stochastic behavior. In particular, we detail the phases in attempting to choose suitable parameters and create such graph displays as will permit an observer to witness the incremental growth of a bell-shaped curve. We argue that the process of building the model, and in particular the accountability, motivation, and frustration experienced, were conducive to ‘connected learning’ (Wilensky, 1993), through which the design of this microworld is grounded. The microworld is part of “ProbLab,” a suite of Probability-and-Statistics models, which in turn is part of “Understanding Complexity,” a middle-school curriculum, currently in development. Introduction Equidistant Probability 1 (EP) is a microworld written in NetLogo (Wilensky, 1999)—a multi-agent parallel-processing modeling environment—as part of an effort of the CCL (Center for Connected Learning and Computer-Based Modeling, http://ccl.northwestern.edu) to create software packages that support middle-school students’ learning of probability and statistics. The microworld and associated activities are intended to draw on students’ domain-relevant personal experience and intuitions (see also Wilensky’s, e.g., 1997, Connected Probability). The design of the EP microworld was done primarily by the first author (DA) guided by the second author’s work on “Connected Probability” and inspired by Papert’s call for increased attention to stochastics (Papert, 1996). The design was informed by a search for an environment that could pithily convey stochastic behavior as well as the workings of tools for calculation and display that describe statistical aspects of this behavior. We wished to create in this environment a suite of models, employing a single interface, that would address issues of probability from multiple directions. The result was 1 EP is available for free download at http://ccl.northwestern.edu