Development of a resource for the teaching of chemical formulas and its appropriation by teachers

International audienceTeaching the symbolic language, the concepts of submicroscopic and macroscopic models, of the empirical register should be done in a dialectical way to encourage the students to make links between the different registers and levels. The symbolic language acts as a bridge between macroscopic and submicroscopic levels. Relying on the history of chemistry makes it possible to highlight the reasons that have led to current chemical formulas. Therefore, we designed a resource based on the controversies in the history of chemistry. We followed a method close to that of the Model of Educational Reconstruction to develop a resource on the introduction of chemical formulas for grade 8 students in France. The resource was proposed to four teachers and implemented by two of them. The principal steps and results of the process are presented