This study examined how readily teachers learn the components of the troubleshooting model of Tillman (1982) via a guided design approach, the consistency of the language of the model with the language of teachers, and the concerns teachers express about guided design as an instructional innovation. Forty-five teachers enrolled in a graduate level course in instructional supervision participated in the guided design exercise, "Right or Wrong Triangles," which introduces and requires application of the model. The exercise uses a transcript of a high school mathematics class as the basis for individual and group activities in identifying classroom problems, suggesting possible problem causes, and proposing solutions. Results indicate that the group exercise was an effective tool for student exploration of the troubleshooting model. With regard to stages of concern about innovation, the group is typical of non-user groups in having high concern for information and fewer for consequences and collaboration. For about one third of the group, additional discussion about guided design should focus on the teachers' personal reservations in using it and similar alternative techniques. The guided design exercises used in the study are appended. (LMM)