This research work focuses on the analysis of the teacher's action and his interactions with students in the field of digital studies in the Nigerien context. The objective of the study is to analyse the teacher's action, his didactic and formative practices. The work consists of eight chapters. The first one includes a presentation of the educational context of Niger. The second presents the theoretical tools, the previous works related to our research objects, and the general problematic of the work. The third part is devoted to the methodological approach which bases the study on the analysis of textbooks, classroom videos and in situ observations. The fourth part examines the mathematical resources used in primary school in Niger. The fifth and sixth parts analyse empirical sessions to study the knowledge at stake in didactic situations. The seventh part proposes an innovative in-service training scheme on collective lesson design in a Cellule d'Animation Pédagogique (CAPED).In the eighth and last part we present a synthesis of our results.