The present paper deals with the chemistry that is taught in schools from an epistemological and cognitive approach. We wonder about the meaning that can have the discipline for those who learn without identifying with the academic purposes because they are elementary school students working in a specific context (the school). From this reflection, we propose a chemistry course for initial training of elementary school teachers with a modeler orientation. From an epistemological point of view we are working with the notion of 'theoretical model', which is derived from current cognitive philosophy of science's perspective, which proposes a semantic concept of a scientific theory facilitating the approximation of the phenomena and the theory that explains them. The cognitive dimension leads us to identify the consistency between the experimental interventions of students, their abstract representations and the language they use to explain what they do, what happens and why happens when they intervene in chemical phenomena. We identify the modelling process with a progressive fit between the three dimensions of human cognition to acquire the Chemical Change Model that guides and gives coherence to the lessons. Narratives were used that kept the interest of students and they refined their explanations during the modelling process. Discourse analysis of students during the learning process enabled us to identify the relations students established between their representations and their experimental interventions and the language they used. All this brought a new perspective to assess means for students to progress and to establish comparisons between them.