Even when following best practices for participatory design, the appropriation of tools in formal education settings can be hampered by a number of factors. Drawing from a case of a web tool built to help teachers in five school districts find and share free resources in an educational digital library, we describe patterns of tool use and provide some explanations for variability in tool appropriation. We also suggest that future research consider school districts as complex systems of professionals whose interactions and inter-relationships may yield unexpected technology adoption behaviors.