This article presents and illustrates a proposed application of concept maps in chemistry teaching in high schools. The students were provided with the "concept lables" necessary for map building in three different ways. The analysis of the students' maps at different stages of the learning process led to the recognition of the three types of cognitive events which seem to correspond to the same number of restructuring stages in the conceptual organization. This can enable the teacher to characterize the changes produced in the learners' conceptions by teaching / learning activities. Three examples of the use of concept maps in chemistry teaching are reported and discussed with reference to: atomic structure, oxidation-reduction and thermodynamics.

A novel didactic sequence is proposed for the teaching of chemical equilibrium. This teaching sequence takes into account the historical and epistemological evolution of the concept, the alternative conceptions and learning difficulties highlighted by teaching science and research in education, and the need to focus on both the students’ learning process and the knowledge to learn.

Throughout the centuries, the concept of element has undergone a clear evolution from a strictly philosophical area to the scientific domain, although the conceptual progress has not always gone along with a terminological evolution. Some inconsistencies in the definition of element can be found in several precollege and university-level textbooks, which creates confusion about the concepts of element and of simple substance and raises a teaching problem. In this paper, a survey of the historical evolution of the idea of element is followed by the critical review of some definitions of element found in the scientific literature and in textbooks. We discuss a definition of element consistent with current scientific knowledge that overcomes the ambiguity between the concepts of element and simple substance at the level of instruction.

A didactic sequence is proposed for the teaching of chemical\ud equilibrium law. In this approach, we have avoided the kinetic derivation and the thermodynamic justification of the equilibrium constant. The equilibrium constant\ud expression is established empirically by a trial-and-error approach. Additionally, students learn to use the criterion of comparison between equilibrium constant and reaction quotient to predict the direction of reaction. The teaching sequence takes into account the alternative conceptions and learning difficulties highlighted by teaching and research in science education and the need to focus on both the students’ learning process and the knowledge on how to learn

RDST Mohamed SOUDANI, Olfa SOUDANI-BANI, Ezio ROLETTO… 180RDST | N° 9-2014 ABSTRACT • Semiotic operating and construction of models in chemistry. A Peircian analytical framework Our contribution consists of a semio-epistemological analysis of the process of modeling of matter and its transformations, especially during the late eighteenth and early nineteenth centuries, mobilizing Peirce's semiotic theory for an analytical framework. In accordance with contemporary physicists' defi nition of modeling, this theory enables us to approach the experimental fi eld as a set of signs that extends the theoretical at the same time as it founds it in a spiral weave of the triptych SOI (Sign-Object-Interpretant). In addition, this approach makes it possible to highlight the guiding authority the iconic sign exercises over scientifi c reasoning. Far from being a sign of a primitive thought from the remote past, the iconic sign is considered as a true "neo writing", with the status of a privileged heuristic instrument. Used by chemists to probe matter in search of indices of a structure in order to interpret its behavior, it has enabled them, after many controversies, to arrive at a particulate structure, and thus to construct the concepts of atom and molecule. This semiotics, fundamentally epistemological, proposes that these concepts are just hypothetical signs for interpreting the answers to the questions raised by experiments designed for this purpose. Moreover, this new perspective on the history of chemistry promises to transform this history into a laboratory for the didactics of chemistry. Thus the iconic sign could serve as a link in or a marker of the evolution of the pupil's chemical thought just as it is for the scientist.