Abstract
This study examines the pedagogical content knowledge of student teachers of biology during their teaching practice in school. The research focuses on the assessment of the teachers' ability to identify their pupils' learning difficulties and characterise their presumed sources. Diaries, kept by 40 student teachers in the course of the two stages of their teaching practice (comprising observation of their mentors in action and their own teaching experience), provided the data for a qualitative and quantitative analysis of the findings. A difference between the two stages was found only with regard to the identification of difficulties: the student teachers identified learning difficulties in most of the lessons they observed, but only in half of the lessons they taught. Their characterisation of the sources of the pupils' difficulties and their recurrence were similar during both stages. The sources of the difficulties were defined according to four categories: the pupil's cognitive and affective characteristics, the type of content, the teacher's methods, and factors inherent in the lesson. The characteristics of the pupil were considered the most frequent source of the difficulties. The study points to the need to increase the teacher educators' awareness of the important role of didactic processes, aimed at exposing the student teachers to their pupils' learning difficulties and help them deal with them effectively.