This communication is based on the study of an instructional sequence of music designed for primary schools in France. Pupils (aged 8 to 10) learn how to play a musical instrument of the brass family, in three primary schools during school time. The schools are located in an area where the population is in a difficult situation. Art Teachers come from the Regional Music School in Rennes (France). The research concerns 60 pupils for 1 year.

A lot of research in several countries have shown that such experiences with music can have positive impact on children’s development (Portowitz, Lichtenstein, Egorova & Brand , 2009). Our purpose is to explore this question by studying didactic action in situ. In the presentation, we will give a typical example of an analysis of teaching a musical instrument in the context of a training orchestra. This is the third course and students have already learned to play C,D,E,F,G. In this session the teacher's main goal is to have the children play in tune and together.

The research questions are:

• what skills are taught to students learning to play an instrument within the context of an orchestra in primary school?

• How do they acquire this knowledge from the joint teacher / student action?

• To what extent can this knowledge help students learn the skills necessary to "work together" in the school and outside?

To do so, we propose a detailed description of the situation with the concepts of didactic contract an didactic Milieu (Brousseau,1997; Sensevy, 2011, 2012)in musical instrument teaching. We will argue that the teacher’s work and the pupils' feedback can be considered as a work of equilibration between the didactic contract and the didactic milieu, in a semiosis process (Sensevy & Forest, 2012).

This intervention is also a contribution to the Joint Action Theory in Didactics wich focus on the relationship between teaching and learning, with a comparative didactics perspective.In doing so, we will try to show how the JATD may contribute to the construction of a science of instructional practice (Koschmann, 2011) in music. We especially focus on three main elements of the theory: the notion of learning game; the contract-milieu didactical relationship, that we call the equilibration process; the semiosis process.We would like to expand the discussion including a sociological dimension, with the concept of “Figuration” introduced by Norbert Elias (1939), perceiving the social world as an interdependence between the individual and society.

Brousseau, G. (1997) Theory of didactical situations in mathematics. Dordrecht: Kluwer academic publishers. Forest, D. (2009). Agencements didactiques, pour une analyse fonctionnelle du comportement non-verbal du professeur. Revue française de pédagogie, 165, 77-89. Elias, N. (1939/1991). The Society of Individuals. Oxford: Blackwell. Foucault, M. (1973). The Birth of the Clinic: An Archaeology of Medical Perception. London: Tavistock . Hall, E. T. (1963). A system for a notation of proxemic Behavior. American Anthropologist, 65, 1003-1026. Koschmann, T. (2011). Theories of Learning and Studies of Instructional Practice. New-York: Springer. Portowitz, A., Lichtenstein, O., Egorova, L. & Brand , E. (2009). Underlying mechanisms linking music education and cognitive modifiability . Research Studies in Music Education, 31(2), 107 -128. Sensevy, G. (2011). Overcoming Fragmentation: Towards a Joint Action Theory in Didactics . In B. Hudson & M. Meyer (Eds.), Beyond Fragmentation : Didactics, Learning and Teaching in Europe (pp. 60-76). Opladen and Farmington Hills : Barbara Budrich. Sensevy, G. (2012). About the Joint Action Theory in Didactics. Zeitschrift für Erziehungswissenschaft. Berlin: Springer Sensevy, G. & Forest, D. (2012, July). Semiosis process in instructional practices. International Conference of the Learning Sciences, Sydney, Australia.