The goals of this project were to: a) carry out the evaluation of a learning system for teaching Civil Engineering students to use Geographic Information Systems software within the context of relevant problems and b) explore the efficacy of iterative usability testing as a tool for development of learning technologies. A series of three usability tests were conducted based on an initial proposed design of the learning system. In general, the results pointed to the role of the learning system as a support tool, and a consequent design that focuses on progressive scaffolding, flexibility, and logical consistency. The results also supported the efficacy of usability testing, in that iterations of the system improved as development progressed. Finally, the importance of scarce resources and education of the development team on the role of usability testing, were identified as central factors in determining the effectiveness of usability testing.