When thinking about teaching, the pedagogical content knowledge of teachers cannot be ignored. We argue that pedagogical content knowledge is a major determiner of teaching practice and is central to teachers' curriculum decision-making at the classroom level. This paper takes a sociocultural perspective on the importance of developing teachers' pedagogical content knowledge. From our classroom-based research in technology education and the past research on pedagogical content knowledge we propose a model of pedagogical content knowledge with seven characteristics that we believe are important for effective teaching.