Abstract: This paper presents the design and application of a web service architecture for providing shared access to web-based visual representations, such as dynamic models, simulations and visualizations. The Shared Representations (SR) system was created to facilitate the development of collaborative and co-operative learning activities over the web, and has been applied to provide shared group access to: a high-resolution image viewer, a virtual petrological microscope, and a forces and motion spring simulation. As well as explaining the architecture and three applications, we briefly present the findings from a user study looking at primary school children’s use of a shared spring simulation. The study findings indicate that shared access to a web-based simulation complements exploratory discussion and enables learners to demonstrate their understanding of a subject. Future work will explore how the system can be combined with dialogic support and embedded in activities to encourage learners with contrasting opinions to discuss and resolve their differing perspectives.