This paper, from the UK group in the STTIS (Science Teacher Training in an Information Society) project, describes research into the nature of teachers' transformations of computer modeling, and the development of related teacher training materials. Eight teacher case studies help to identify factors that favor or hinder the take-up of innovative computer tools in science classes, and to show how teachers incorporate these tools in the curriculum. The training materials use the results to provide activities enabling teachers to learn about the tools and about the outcomes of the research into their implementation, and help them to take account of these ideas in their own implementation of the innovations. © 2004 Wiley Periodicals, Inc. Sci Ed89:56–70, 2005