La communication pédagogique en cours magistral de chimie: Peut-on en améliorer l'efficacité ?

During the first academic year, chemistry courses are central and constitute a major source of difficulties for many students. Among those stand the omnipresent changes, most of the time implicit, between the macroscopic, microscopic and symbolic levels. Establishing links between the three levels is neither obvious, nor automatic for students, although this process is a condition to understand "chemistry" thoroughly. In this paper, we will point out the characteristics of the message given by the teacher during six lectures and show how it is closely linked to this omnipresent difficulty. We will propose specific actions and practical tools aiming at improving the educational communication but also present the impact of their implementation on the knowledge gained by students.