We present our initial report on Project GeoSim: a multidisciplinary effort involving members of the Departments of Geography and Computer Science at Virginia Tech to develop computer-aided instruction (CAI) software for the teaching of introductory geography. Project GeoSim will apply the immense capabilities of Geographic Information Systems (GIS) and simulation to the teaching of geography, beginning at the first geography course. Our computer-aided educational materials will be usable by a wide range of students, focusing in particular on first-year undergraduate and high school students. Initially we will provide a series of computerized laboratory modules applicable to several introductory geography courses. These modules must meet several criteria such as being highly interactive, appropriate for computer novices, incorporating a Geographic Information System (GIS) and simulation when appropriate, and able to run on a wide range of moderately priced equipment. This paper presents the overall project, and describes the working prototypes for two of these modules: Mental Maps and International Population.