StatPlay is a collection of computer-based demonstrations and interactive simulations intended to promote cognitive change and good understanding of central aspects of statistics and experimental design. StatPlay is intended for use in a variety of ways, including lecture demonstrations, by groups and by individuals. In addition to free exploration, challenging tasks--some in game formats--offer structure and guidance to the learner's activities. With support from the Committee for the Advancement of University Teaching (CAUT) StatPlay is being developed in Visual C++ for Windows. It currently comprises microworlds, or Playgrounds, for working with: discrete datasets; continuous distributions; sampling; confidence intervals; and hypothesis testing. Recent development has focussed on representations and activities that help students acquire good understanding of confidence intervals, simple hypothesis testing, and the relation between these. We will demonstrate the software, describe use of StatPlay by students and report an experiment evaluating students' conceptual change.
