Étude des pratiques enseignantes pour la transformation de savoirs scientifiques et leur enseignement en vue d’un changement des conceptions des étudiants

Science education in the context of the competency-based approach presents pedagogical and didactic challenges. Among other things, teachers have to choose relevant content and teaching methods that will promote the development of targeted skills in science courses. Chemistry is also a complex discipline that some students have difficulty understanding. This is explained by the fact that the knowledge underlying it is abstract, often invisible to the naked eye and embodied in several levels of representation (microscopic, macroscopic and symbolic). These particularities justify the need for teachers to transform the knowledge of this discipline into forms that are easier for students to learn. Our research has focused on the teaching of a specific theme, namely the teaching of the probabilistic model of the atom, which stipulates that electrons are found in orbitals describing regions of the atom where the probability of finding an electron is high, since it is recognized in the literature that it presents particular obstacles to learning. Some studies have shown that the difficulties are in particular due to the fact that the learning carried out in secondary school on previous atomic models seems to persist and interfere with new learning or that it is linked to the abstract nature of concepts relating to quantum mechanics. Our research aims to better understand the teaching practices of knowledge transformation related to the probabilistic model of the atom during the planning phase as well as teaching practices related to the knowledge learned by students in the "General chemistry" course that is part of the Natural Sciences Program. The transformation process that is part of Shulman's model of reasoning and pedagogical action (1987), that emerged from his work on pedagogical content knowledge, was used to study knowledge transformation teaching practices. For the study of effective practices in the interactive phase of teaching, the concepts of reflection in action and reflection on action from Schön’s work (1994) and an integrated model of interactive teacher thinking (Wanlin and Crahay, 2012) are mobilized. The knowledge learned by the students was addressed in relation to the concept of conceptions (also called representations) describing these ideas, this knowledge that the students already have at the time of learning. We have chosen to interpret these conceptions and the change of these with the notion of levels of formulation. A multicase study was conducted with six chemistry teachers using semi-structured and stimulated recall interviews, which compared reported and actual practices. Explained diagrams made by their 163 students before and after the teaching of the sequence made it possible to highlight the changes in their way of conceiving the structure of the atom. Finally, interviews were conducted with 10 students to highlight some of the practices that have contributed to the change in their conceptions. A qualitative analysis was performed on the data collected. The results show a diversity in knowledge transformation teaching practices, although many of these are shared by several teachers. For the preparation of the lesson and the choice of the essential contents, teachers consult essentially the same sources (course manual, curriculum documents, colleagues) while the criteria on which they base their choice of essential content differ. Different forms of content representation are used primarily for the purpose of arousing student interest or explaining or illustrating certain concepts. Although the lecture remains widely used, teachers plan more active learning activities in order for students to practice, to allow them to make connections themselves, to introduce them to concepts by helping each other and to verify their understanding. Finally, teachers adapt their planning closely to the cognitive characteristics of their students, to their previous knowledge of atomic models, and the planned strategies differ from one teacher to another. Actual practices observed in the classroom generally correspond to what was planned for the majority of teachers. However, they come to take decisions in the action that lead them, in some cases, to make changes to their plan on the fly. These decisions emerge mainly from a reflection in action initiated by indices they perceive from students. We also observed some reflections on action as teachers made critical comments about their teaching after the event. These various reflections lead teachers to make changes to their plans over the years, the latter becoming better adapted to the constraints of the situation. This may explain why we observed few differences between reported planned practices and those actually observed. Finally, the research allowed us to highlight some teaching practices aimed at changing students' conceptions. The majority of students conceive the structure of the atom in the manner of the model "Rutherford-Bohr", the latest model taught in high school, when they arrive at their first CEGEP chemistry course. Research has shown that this conception is difficult to change for various reasons. Our results show that teachers are aware of this fact and that some practices seem to have contributed to actual changes in the way students conceive the atom. Examples include the use of forms of visual content representation and the implementation of certain classroom learning activities. We observed that at the end of the session, the majority of students had seen their conceptions evolve significantly by representing the atom according to the concepts related to the probabilistic model even if their representations could contain some errors.

Keyphrases: Teaching practices, Science education, Case studies, Atomic models