Within the field of education, there has been an increasing recognition of the importance of formative assessment and of structural knowledge. In an effort to fill needs in each of these areas, this article describes an innovative feedback strategy intended to improve students' structural knowledge. Twenty-four high school physics students were assessed using Pathfinder networks (PFnets) for their structural knowledge of a just-completed unit on work, energy, and power. As feedback, students were shown both their PFnet and a referent PFnet and were asked to reflect on the differences. In addition, misconceptions regarding the concept of "work" were identified in their PFnets and used to present individualized remedial exercises to each student. Following this feedback/remediation session, students' structural knowledge was again assessed. Results indicate that overall structural knowledge improved following feedback/remediation. In addition, structural knowledge of the concept "work" improved more than a control concept, indicating that feedback plus remediation had a larger effect than just feedback. We discuss the innovative features of the feedback strategy employed: the novel application of a "computer-based" assessment tool to provide "graphical" feedback aimed at improving "structural knowledge." (Contains 2 figures and 1 table.)