In this study, the pedagogical content knowledge (PCK) of four experienced primary school teachers was investigated within the "Let's Solve the Riddle of Our Body Unit". The PCK investigation adopted a learning approach based on inquiry, content representation and pedagogical and professional-experience repertoires (PaP-eRs), and interview forms were used as data collection tools. During the course of the research, the findings obtained from observations made during a total of 18 course hours formed the basic data source of the study. According to the results of the study, in which descriptive and content analysis were used concurrently, primary school teachers lack subject matter knowledge, do not interrogate the pre-knowledge of students and some misconceptions exist regarding about blood moves and exercise with pulse. Additionally, some deficiencies were detected in the curriculum, i.e., it offers non-inquisitional knowledge. Furthermore, teachers employee assessment methods with traditional teaching methods and techniques. In the context of an inquiry-based learning approach, teachers appeared to believe that classroom activities were adversely affected by the physical conditions (class size, lack of laboratory etc.), students' cognitive levels and parent profiles. The result of this study revealed that PCK components affect one another. The PCK findings pertaining to primary school teachers as it concerns the unit are briefly discussed and some suggestions about the development of PCK are submitted.