Extensive research states that achieving Sustainable Development (SD) is a significant challenge due to several severe environmental issues. Education plays a crucial role in addressing this challenge, offering a valuable opportunity to influence the knowledge and abilities of society’s future adult citizens. This thesis, focusing on upper secondary science teaching, used the theoretical framework of Pedagogical Content Knowledge (PCK) and its Refined Consensus Model. The aim was to investigate (1) what content science teachers emphasise when teaching SD, and how they justify that content, (2) how science teachers’ PCK in teaching SD can be captured and developed with a combination of reflection tools, (3) in what ways science teachers adjust their teaching to different vocational education programmes when teaching SD, and (4) in what way teacher teams in science can develop PCK for teaching SD via collective reflections.

The methods included science teachers’ use of reflection tools, semi-structured interviews, and teachers’ collective reflections. Data were analysed using thematic analysis and qualitative content analysis. The results reveal the content choices made by teachers when teaching SD and the justifications behind them. Also, they demonstrate how reflective tools captured and supported the development of PCK. Additionally, the results clarify that many teachers adjust their teaching to the different vocational education programmes when teaching SD. Finally, the results show that collective reflections in science teacher teams may develop teachers’ PCK.

This thesis contributes to the field of PCK research with a specific focus on SD. The implications translate into recommendations for principals and teachers who will hopefully be inspired by the results and the reflective tools used in the study.

This thesis aims to contribute knowledge about how science teachers’ knowledge related to teaching Sustainable Development (SD) can be captured and developed from individual and collective perspectives. The thesis focuses on upper secondary science education and is grounded in the theoretical framework of Pedagogical Content Knowledge (PCK) and its Refined Consensus Model. Qualitative methods were used, such as teachers’ use of reflection tools, interviews, and collective reflections by teachers. The results reveal the content choices made by teachers when teaching SD, along with the justifications for these decisions, and that reflective tools capture and facilitate the development of PCK. The results indicate that many teachers adjust their teaching to different vocational education programmes when teaching SD. Further, the results show that collective reflections within science teacher teams can potentially develop teachers’ PCK in teaching SD. The thesis offers recommendations for school leaders and teachers, encouraging them to draw inspiration from both the reflective tools and the findings presented in this thesis.