This article aims to investigate relationships between the different realms of PCK by referring to the refined consensus model of PCK. We conducted a pre–post study with an intervention using a video-based simulated learning environment to measure different realms of PCK of 78 pre-service biology teachers. The participants were randomly assigned to three groups receiving different treatments in the form of scaffolds while working on the learning environment during the intervention. Only the participants receiving scaffolds referring to their personal PCK significantly improved from the pre-test to the post-test (F_pPCK(1,27) = 9.592, p = 0.005, partial η² = 0.262, n = 28). These scaffolds encourage participants to use their prior knowledge when reflecting on instructional quality, as shown in the simulation. Although the findings of the present study support the theoretical view of the refined consensus model of PCK, more focus on the personal PCK could be helpful to understand how PCK is acquired and organized “within one teacher”.

Diagnosing is an important aspect of teachers’ professional competence. To successfully diagnose classroom situations, one has to apply pedagogical content knowledge (PCK) in diagnostic activities (DA). Simulated classroom situations with embedded scaffolding can be an effective way of practising skills needed to foster diagnostic competences. In an intervention study with pre-post-test design using the video-based learning environment DiKoBi, we investigated the effects of scaffolds on the diagnostic competences of 57 pre-service biology-teachers in an early stage of university education. For the intervention, we developed two types of scaffolds: one providing additional PCK (PCK-scaffold) and one focusing on the diagnostic activities (DA-scaffold). Pre-service teachers were divided into four groups depending on the type of scaffold they received during the intervention (PCK-, PCK + DA-, DA- and control group). Pre-service teachers receiving PCK-scaffolds showed statistically significantly higher diagnostic competences in the post-test than in the pre-test. This includes the PCK- as well as the PCK + DA-group. For the other two groups, no significant improvement can be reported. Thus, we assume that the diagnostic competences of pre-service biology teachers can effectively be fostered by including PCK-scaffolds in DiKoBi and hence a minimum of PCK is necessary for successfully diagnosing in simulated classroom situations.