Students begin their study of probability and statistics with strong and often misleading intuitive ideas. This project seeks to confront students' preconceptions and at the same time use them as a source of motivation. Our approach uses the counter-intuitive side of probability to "rope students in" - to capture their imagination and force them to think. We are developing a Web site with interactive, Java-based, material that can be used in introductory probability and statistics classes for both specialists and non-specialists, from AP courses through upper level college courses. The site will include: simulations; animated scenarios; links to background material in mathematics; interactive Venn diagrams, probability trees, and densities as limits of histograms; historical material related to probability and statistics; and graphical animations. But the heart of the site will be a collection of modules that surprise and engage students - the "Gotcha!" of probability. We exploit the observation of Laplace -- "The Mind, like the sense of sight, has its illusions; and just as touch corrects those of the latter, so thought and calculations correct the former. Recent work of cognitive psychologists informs this project in two ways. First, it identifies students' preconceptions and the barriers they create for understanding probability. Second, it will guide the development of effective educational uses of the rich array of multimedia and interactive technologies available via the Web.
