The recent French schools reform (2009) was accompanied by a change in mathematics curriculum. With respect to the "classe de seconde" (9th-10th Grade in US High School), two subjects question us: first, the new positioning of algebra, now part of the functional domain, giving it a primary role of tool, and on the other hand, the introduction of algorithmic concepts. Through the value of combining these two subjects, this thesis proposes a didactic study of the resumption of elementary algebra in "classe de seconde", and especially of the objects orbiting around equation concept, objects of which we search to refine the meaning, through the detour of algorithmics. Positioned within the anthropological theory of the didactic by Chevallard, we study the conditions and constraints of this resumption. Through a didactic engineering implementation in collaboration with three high school teachers, we show how the resumption of basic algebra concepts through algorithmics induced for students a gesture of generalization, while achieving some materialization of algebraic objects, manipulating them in a computer program. For teachers, this engineering induces a questioning of their praxeology teaching algebra, generated by non-routine tasks of equations categorization and modeling. Finally, we highlight the challenge of integrating algorithmics domain within mathematics discipline and the need for teachers to be trained, to ensure the viability of this teaching.
