Pedagogical content knowledge (PCK) of a science teacher: reflection and action as facilitators of learning

A case study of an experimental secondary school science teacher over time in different periods is presented. The scope of study focuses on School Learning and Obstacles in the teaching-learning process. It starts from a complex vision of professional knowledge and is developed in three different phases, related to school innovation and the type of content that is implemented: Solutions and Soil Formation. The results show a teacher's development associated with the strength of previous knowledge of the topic, but limited by the difficulty of assuming full constructivist positions regarding student-learning and how to collectively study learning difficulties in the classroom. Some implications arc established in relation to the initial training of teachers.