Cross-disciplinary training in the earth sciences is a difficult issue that has elicited concerns in academia and industry. Many problems associated with cross-disciplinary training stem from the fact that the earth sciences have evolved as a collection of loosely related, poorly coordinated specialties with little communication or interaction between them. As a result, when asked to teach across disciplinary boundaries, our instinctive reaction is to provide a watered-down version of the details that we teach our own students rather than the conceptual understanding that will help others work with us. This makes it difficult for earth scientists to provide the public with a coherent education in the fundamentals of earth science, and it has impeded the development of a common foundation for interaction between earth-science specialists. We have designed a computer-based learning environment for use in cross-disciplinary, earth-science education. This environment entails more than simply providing traditional course materials in an electronic form. Rather, the relevant material is conveyed through the use of a generalization of the case-study approach we refer to as the interactive case study approach. Through the use of computer simulations, students are allowed to interact with all aspects of the case, thereby helping them to become comfortable with the thought processes employed by a specialist and develop an intuitive understanding of the underlying physics. This educational model has been applied to the development of an introductory course in geophysical exploration geared toward upper-level undergraduate students not majoring in geophysics. The cases used in the course are couched in terms of a request for bid (RFB) requiring the use of a specific geophysical technique to solve a specific geologic or engineering problem. In responding to this RFB, students must write proposals, design geophysical surveys, interpret data derived from these surveys, and report on their results. All of these activities are supported through an interactive World Wide Web-based environment, and all are aimed at helping students develop an intuitive understanding of the nature of geophysical exploration and the subsurface constraints that can be derived from geophysical observations. The materials associated with the course are available for public use by all at a a url http://www.mines.edu/fs_home/tboyd/GP311 .