In this article we present and discuss some theoretical and methodological elements of a wider research that analyzes the teaching practice of two teachers novice and expert from a semiotic theoretical approach. The conceptual framework of this work allows for addressing the epistemological and didactic dimensions of the teaching practice. Three concepts are particularly emphasized: sign, artefact, and mediation. Furthermore, we propose, through the networking of theories (Kidron & Bikner-Ahsbahs, 2015), the teacher's teaching model as a theoretical-methodological construct to analyze the teaching practice. This work reports the teaching model for the phenomenon of a free-falling object, in which the close relation between mathematics and physics is addressed. Some results on the application of the teaching model are presented for the analysis of a novice teacher. [For the complete proceedings, see ED606556.]