The research presented here focuses on the use of resources by primary school teachers. We adopt here a broad acceptation of resources, like Adler (2000) who distinguishes between material, human, and socio-cultural resources. The resources we consider can be curriculum material (Remillard 2005), including in particular ICT tools; but a discussion between two teachers, the observation of students' activity are resources as well. The questions we study can be formulated as follows: − Which factors govern the acceptation, or the non-appropriation of a resource by teachers? − How is a resource transformed, combined with others by a teacher for classroom use? − How do the resources elaborated by the teacher intervene in the students' mathematical activity, and how does the classroom use influence the teachers' choices? We retain a perspective inspired by cognitive ergonomy. Rabardel (1995) proposes to distinguish between an artifact, social and cultural product of human activity, available for a given user, and the instrument that s/he develops in integrating it in her/his activity. Extending this distinction, Gueudet and Trouche (2007) introduce a distinction between a set of resources, and a document developed by a teacher or a group of teachers drawing on this set of resources. The document includes combined extracts of the initial resources, but also a psychological construct. The development process is called a documentary genesis. For the students, we consider the resources introduced by the teacher in the classroom as ostensives. Indeed, for Bosch and Chevallard (1999), the mathematical activity consists in manipulation of ostensives (symbols, sounds, material objects, etc.) adjusted by non-ostensives (ideas, methods, etc.). These resources are thus ostensives owning an instrumental and a semiotic function, influenced by the teacher's choices (Poisard, 2005). The students' use of these ostensives and, more generally, what happens in class influence the teacher's further choices. We study this particular form of teachers and students joint action (Sensevy and Mercier 2007). In this communication, we use such an approach in the context of the teaching of geometry at primary school. We are involved in a research group with three primary school teachers (this group is inserted in a larger national researcher project, GUPTEn: genesis of professional uses of technology by teachers; however in the part of our work exposed here we do not focus on technology). Each of these teachers designed a teaching of symmetry, drawing on a wide range of resources: textbooks, material, e-exercises (we proposed an e-exercise basis called Mathenpoche, Bueno-Ravel and Gueudet 2008), dynamic geometry software (Declic, Ostenne 2008). We asked them to describe the sessions planned according to a grid we proposed, thus this grid also intervened as a resource. We observed the unrolling of some of the sessions (the class involved corresponded to grade 3, 4 and 5, with pupils 8 to 10 years old). We analyse some tasks proposed to students with specific resources (a sheet of paper and e-exercises basis in particular) and ostensives and show that the tasks are led by precise mathematical techniques and technologies (Chevallard, 1997).

The teachers observed worked within the research group. The researchers proposed two kinds of resources: the ICT resources, and a grid for the description of sessions. The data were collected through: − observation of the teachers' preparation work: direct observation, and description by the teacher during the group meetings; − collection of the teachers' productions; − observation and recording of classroom sessions.

We observe and analyse the integration, or the non-acceptation of resources by the teachers. We discuss their choices, and the associated reasons: possibility of combining a new resource with already integrated resources; didactical objectives like the association of various kinds of ostensives for the students, and more general teachers' convictions. We describe the integration processes, the teachers' documentary geneses, and in particular the influence on these processes of the students' activity in class.