The moving arrows environment: a digital artifact for mediating the meanings of variable and unknown.

This study, part of a greater research project, describes a digital interactive artifact designed for mediating the mathematical meanings of variable, constant, functional dependency, structure and value of a linear literal expression, and relationship between two expressions depending on the same variable. We present the a-priori analysis of the semiotic potential of this artifact and the a-posteriori analysis of its actual unfolding in the context of a pre-experimentation with low achieving students (aged 15-16). In particular, we focus on the signs produced by these students during the accomplishment of exploratory tasks involving the artifact.