As noted by Kinach (2002), teacher educator must challenge their preservice teachers ‘‘habitual ways of thinking about subject matter and subject matter teaching’’ (p. 69). These case studies uncovered an important consideration in the development of TPCK—the interaction of the content of science/mathematics and the content of the specific technology. Terry extended his lessons to have his students investigate the effects of the external environment on the temperature reading, redesigning the probe ware setup to improve the data collection. Yet, when the integration was a natural inclusion in the unit, Karen resisted using class time to explore the science embedded in the design of the technology. Denise simply rejected the consideration of the science of the technology thinking of the technology as a tool to do science rather than a tool embodying science.