This paper presents a model that was developed for the categorization and evaluation of stand-alone interactive media and that now is used to contribute to a more detailed and specific educational discussion of Internet use. The paper begins with a review of the foundations on which the model is built, including software as subject, tool, or medium and the three dimensions of the learning model--learning/teaching, action, and social organization. The following types of Internet applications are then discussed from the perspective of the learning model: (1) learning facts and rules (remember, receive); (2) rules, procedures (apply, imitate); (3) problem solving (decide, select); (4) Gestalt perception, pattern recognition (explore, understand); and (5) complex (real) situation (invent, master, cooperate). Existing World Wide Web sites are described as examples in each category. Features that distinguish Internet applications from stand-alone educational software are summarized. Two figures illustrate the three-dimensional heuristic model of learning and social organization of the learning process. (DLS)