Resumen
The particulate nature of matter is a fundamental concept in science that students in lower grades find difficult to understand. Pedagogical content knowledge (PCK) has been identified as germane for addressing difficult topics and it enhances effective learning. The purpose of this study was to capture the quality of the enacted PCK that practising and pre-service teachers activate during planning. Data were collected through a validated PCK questionnaire which was completed by both practising and pre-service teachers. A rubric was used to code their responses. A Rasch analysis model was used to analyse the five components of the topic-specific PCK construct. Data from an item analysis show that pre-service teachers found the test items to be less difficult than did the practising teachers. We found that there was a statistically significant difference between the two groups of teachers in terms of knowledge activated during planning. These findings show that, in transforming the topic content and concepts of the particulate nature of matter, the pre-service teachers integrated more components of enacted PCK compared to practising teachers. Discussions around the curriculum for both groups of teachers might provide insight into the design of future teacher development programmes.