This study proposes the use of case-based reasoning to help educators design with Web 2.0. Principles for designing a web-enhanced case-based activity (CBA) were used to design an online professional development course for a group of 16 in-service educators. The Learning in Context model was used as a scaffold to help participants in their design of activities. Formative evaluation points toward the utility of this approach, and rich description is provided to help readers assess the findings. Findings related to the use of CBA design principles include: the possibility of using open resources to build case libraries; the importance of using expert cases analogous to the needs of participants; the importance of direct and soft scaffolding; the need for feedback, reflection and design iteration; and the perceived usefulness of the Learning in Context model as a scaffold. An unexpected finding was how hands-on familiarity with the tools appeared to be a prerequisite for participants to engage in the expert case exploration, and to design with Web 2.0.