This study explores the rationale, efficacy, and social validity of a professional development model designed to move elementary school science activities closer to the practices of working scientists as required by the United States’ “Next Generation Science Standards.” The model is culturally sensitive and aims to create experiences with high subjective task value. The formal theory of change uses scaffolding, Piagetian agency, and Vygotskian learning opportunities to argue that culturally familiar representational tasks in culturally natural intersubjective contexts can lead to work prototypical of scientific modeling under particular facilitation conditions: when participants (a) are allowed free use of their cognitive and culturally native tools; (b) work in open dialog amongst themselves and with a science cultural adept; (c) work in groups in contexts that represent cultural aspects of science work; (d) are pressed to follow some of the epistemic and ontological imperatives of working science; and (e) maintain their agency in resolving cognitive conflict. The study implemented the model with fidelity as a professional development workshop around exploring physics with simple, everyday materials over two afternoons with a small group of elementary-school teachers in southern Appalachia. Analysis indicates that participants engaged in representational tasks with little off-task behavior, exhibited all of the targeted modeling behaviors, felt all components were inherently interesting and useful, and rated the workshop highly as professional development in science teaching but lower as coherent with local evaluation standards. Data on outcome-expectancy beliefs were largely inconclusive but may suggest that the workshop caused teachers to doubt their current ability to teach science to their students. The workshop model provided “cultural modeling” and access to participants’ “funds of knowledge,” created a “third space,” and attended to intrinsic task interest as recommended in the National Research Councils’ How People Learn II. Overall, the study endorses using genuine dialog around teachers’ descriptions and explanations of the physical world to bridge native cultural norms and behaviors with science practices.