The purpose of this exploratory study was to describe the changes in middle school teachers' planning of science activities during a teacher enhancement project that involved problem-solving instruction and classroom implementation of a problem-solving curriculum model. The model reflected the cognitive science perspective and integrated the following features: students' prior knowledge, declarative knowledge, general strategy and domain-specific strategy knowledge, and instructional strategy. Twenty-eight teachers received instruction in human biology topics in five two-day workshops, in strategic pedagogy and curriculum design in two intensive three-week summer workshops, and in classroom implementation of the curriculum model in five workshops during the subsequent school year. Teachers were interviewed at three points: before and after summer workshops and after classroom implementation. Transcripts were analyzed using pre-decided categories and frequency distributions of categories calculated. Analyses indicate that increased involvement resulted in more complex patterns of planning with more emphasis on salient features of the curriculum model. Most dramatic changes occurred in teachers' attention to students' prior knowledge, which rose during the implementation phase of the project. Contains 23 references. (Author)