Science teachers’ pedagogical content knowledge (PCK) has been researched in many studies, yet little empirical evidence has been found to determine how this knowledge actually informs teachers’ actions in the classroom. To complement previous quantitative studies, there is a need for more qualitative studies to investigate the relationship between teacher knowledge (as formulated by the teacher) and classroom practice, especially in the context of an educational innovation. In this study we explored a possible way to investigate this relationship in an in-depth and systematic fashion. To this end, we conducted a case study with a chemistry teacher in the context of the implementation of a context-based science curriculum in The Netherlands. The teacher’s PCK was captured using the Content Representation form by Loughran, Mulhall, and Berry. We used an observation table to monitor classroom interactions in such a way that the observations could be related to specific elements of teachers’ PCK. Thus, we were able to give a detailed characterization of the correspondences and differences between the teacher’s personal PCK and classroom practice. Such an elaborate description turned out to be a useful basis for discussing mechanisms explaining the relationship between teachers’ knowledge and teachers’ actions.

The aim of this study was to explore how the design of this chemistry lesson for citizenship influences students’ use of different perspectives in decision-making about ‘the use and sale of laughing gas’. In this study, ‘the use and sale of laughing gas among youth’ was chosen as a socio-scientific issue. This chemistry lesson for citizenship was designed according to the 5E instructional approach, and activating pedagogical methods and tools (i.e., group discussion, reading the information cards, taking notes, watching instructional videos) were used. Both the types of perspectives used and the effectiveness of the pedagogies implemented were explored. Twenty-three students from two classes participated in the study. The data were collected through five tools (four worksheets and a questionnaire). The students mainly used ‘scientist’ perspective by focusing on what research says about the possible consequences of inhaling laughing gas. The students also focused on ‘health’; principally, they referred to the relation between the amount of laughing gas used and the damage it may cause. As to the influential pedagogical elements of the lesson, the ‘videos’ were found to be the most effective and informative. In addition, the ‘group discussion’ was also found to be an influential activity of the lesson on making decisions about the use and sale of laughing gas. Therefore, our results suggest that the lesson design supported the students to recognize and use different perspectives to make informed decisions about the sale and use of laughing gas.