National standards that centre on the underpinning epistemic practices of the discipline has emphasised the need for teachers to focus much more on knowledge generation approaches to learning. Adopting a complexity perspective, we attempt to understand how teachers shift over time by examining their epistemic orientation to knowledge generation and their understanding of the nature of the epistemic tools of language, dialogue and argument that underpin these environments. Ninety-five teachers participated in a 2-year professional development programme to implement the Science Writing Heuristic (SWH) approach -- a recognised generative learning approach. Using a longitudinal latent profile analysis of four waves of data, three different teacher profiles emerged (low, medium and high). Teacher transition to higher profiles was not uniform, took time, and required them to engage with the epistemic systems of orientation and tools. The results highlight that teacher PD needs to be tailored to promote richer transitions to implementing generative learning environments.