Requirements development in scenario-based design

We describe and analyze the process of requirements development in scenario-based design through consideration of a case study. In our project, a group of teachers and system developers initially set out to create a virtual physics laboratory. Our design work centered on the collaborative development of a series of scenarios describing current and future classroom activities. We observed classroom scenarios to assess needs and opportunities, and envisioned future scenarios to specify and analyze possible design moves. We employed claims analysis to evaluate design trade-offs implicit in these scenarios, to codify the specific advantages and disadvantages in achieving requirements. Through the course of this process, the nature of our project requirements has evolved, providing more information but also more kinds of information. We discuss the utility of managing requirements development through an evolving set of scenarios, and the generality of the scenario stages from this case study.