Informal design tools can provide immense value during the creative stages of the design process, e.g., by transforming sketches into interactive simulations. Two key limitations of informal and many other design tools are that they do not promote working with multiple design ideas in parallel or collaboration. In this paper, we present a new interaction model that allows a team of designers to work efficiently with multiple ideas in parallel. The model is grounded in theories of creativity and collaboration, and was further informed by observations of creative group work practice. Our interaction model is fully demonstrated within a new system called TEAM STORM. Results from an initial evaluation indicate that design teams are able to effectively utilize our system to create, organize, and share multiple design ideas during creative group work. The benefit of our model is that it demonstrates how many existing single-user design tools can be extended to support working efficiently with multiple ideas in parallel and co-located collaboration.
