This Phase I SEPA proposal supports a consortium of science and education partners that will develop System Dynamics (SD) computer models to illustrate basic health science concepts. The consortium includes Oregon Health Sciences University (OHSU), Portland Public Schools (PPS), Saturday Academy, and the Portland VA Medical Center. SD is a computer modeling technique in which diagrams illustrate system structure and simulations illustrate system behavior. Desktop computers and commercial software packages allow SD to be applied with considerable success in K-12 education. NSF grants to Portland Public Schools have trained over 225 high school teachers in Portland and surrounding areas. Two magnet programs have been established with an emphasis on systems and at least five other schools offer significant systems curriculum. Major components of this project include (1) Annual summer research internships at OHSU for high school teachers and high school students, (2) Development of SD models relevant to each research project, (3) Ongoing interactions between high school science programs and OHSU research laboratories, (4) Development of curriculum materials to augment the use of the SD model in the high school classroom or laboratory setting, and (5) Development of video materials to support the classroom teacher. Content will focus on four fundamental models: linear input/exponential output, bi-molecular binding (association/dissociation), population dynamics, and homeostasis. Each of these models is very rich and may be extended to a broad variety of research problems. In addition these models may be combined, for example to illustrate the effect of drugs (binding model) on blood pressure (homeostasis model). System Dynamics is an exemplary tool for the development of materials consistent with National Science Education Standards. SD was specifically developed to emphasize interactions among system structure, organization, and behavior. Students use these materials as part of inquiry-based science programs in which the teacher serves as a guide and facilitator rather than the primary source of all content information; technical writing by students is also encouraged. Finally, these SD materials will provide a coherent body of work to guide the ongoing professional development of the classroom science teacher.