The purpose of this study was to assess structural knowledge change across a two-week workshop designed to provide high-school teachers with training in Java and Object Oriented Programming. Both before and after the workshop, teachers assigned relatedness ratings to pairs of key concepts regarding Java and Object Oriented Programming. Their ratings were submitted to the Pathfinder network-scaling algorithm, which uses distance estimates to generate an individual's knowledge structure representation composed of nodes that are connected by links. Results showed that significant change in teachers' knowledge structure occurred during the workshop, both in terms of individual teacher networks and their averaged networks. Moreover, these changes were significantly related to performance in the workshop. The results of this study suggest several implications for teaching and assessment in computer science.