A long-term, 2 year in-service provision to develop pupils thinking capability was provided for 91 secondary schools during the period 1998-2002. The science teachers involved reported that the in-service experience impacted on their pedagogic practice. The evidence was gathered through reflective surveys and interviews. The in-service programme engaged the teachers in authentic learning activities. The findings suggest that engaging the teachers in actions or processes which are then transformed into conceptual (scientific and cognitive) objectives can influence their perception of learning. Through collective reflection of their active participation they objectified connections between learning processes and learning outcomes. The explicit reflections of the modelled experiences provided the opportunity for the teachers to empathize, as learners, with their pupils' learning situations. They were guided to reflect on how the nature of social interactions can impact on reasoning and meaning making. The reflective cognitive and learning objectivity of the in-service programme appeared to influence their pedagogy in a variety of ways. The pedagogic changes included a significant increase in pragmatic interpretation and application of learning theories to classroom situations. Teaching strategies were also developed to include: proactive management of collaborative learning; a generally more interactive and dynamic way of learning through questioning; promotion of more prediction opportunities; encouragement of more reflection, in a variety of ways, on the processes by which potential or actual solutions to scientific tasks or challenges were reasoned. As a result of this study pedagogic principles to support learning and cognitive development in science and learning generally are proposed. (Contains 7 figures, 1 table, and 3 notes.)