Students in the introductory computer science courses are faced with a bewildering array of new concepts, ranging from strange (but fundamental) notions like recursion to more mundane concerns such as how to make best use of programming tools. That students benefit from experiential, exploratory reinforcement of these concepts has been the basis of the movement toward closed laboratories in introductory computer science in recent years. Closed laboratories come with their own set of problems, ranging from the need for dedicated laboratory facilities to administrative problems with staffing and scheduling four hour courses with closed laboratory components. This project develops a set of highly interactive tutorial exercises covering topics addressed in the typical introductory computer science curriculum. The exercises allow students to manipulate inputs and guide processes illustrating basic concepts and to observe the effects of their activity visually. These tutorials will be delivered via the World Wide Web, and constructed with the Java programming language. This choice of development language and delivery system has several benefits: the tutorials will be highly platform independent; they will be less server intensive than other Web-based mechanisms for creating interactive applications; dedicated laboratory facilities are not necessary since students can run browsers on their own computers; and CD-ROM versions of the tutorials would allow stand-alone use even when network connections are not available.