The purpose of this article is to explore the subject of the acquisition of teaching knowledge during teaching practices in initial training. At first, from a theoretical review, we try to specify the polysemy of the terms to know and knowledge from the perspective of the educational sciences, and then focus on teaching knowledge and its taxonomy. We propose the distinction of the verbal repertory of teachers as a type of instrumental knowledge fundamental to professional activity. From the research on teacher cognition, we introduce the category of Didactic Repertoire that permits us to contain not only those theoretical-practical knowledges acquired during university or tertiary education, but also those implicit theories that have a direct impact on decision making in effective practices. Through the presentation of examples taken from the data corpus of our research, we realize the existence of a system of beliefs, representations and knowledge (BRK) that influences the activities proposed by the students who carry out their professional practices. Finally, we observe the processes of negotiation of meaning that take place in the verbal interactions between students and teacher-trainers around class planning. This approach gives us two conclusions: firstly, concerning the teaching knowledges, these are contained within a didactic repertoire, constituted thanks to a BRK system. This system, made up of multiple personal experiences of teachers throughout their biography, serves as a basis for decision-making in the classroom. On the other hand, in relation to initial training, the construction of teacher knowledge during teaching practices is the result of a process of negotiation of the meanings assigned to the planned actions.