What is a “good” argumentation in mathematics classroom?

This paper investigates the argumentative processes produced by upper secondary school students during an educational activity designed with the dual goals of introducing classical concepts of probability theory through problem solving and promoting argumentative competence. We reckon that in this context the main function of argumentations is to support probabilistic thinking development. We are interested in investigating how this function influences the development of argumentative processes in the classroom. We analyse two classroom episodes in order to show how argumentative processes evolve in relation to the interventions of the teacher and the peers, and how the changes in the produced arguments reflect the function that argumentation is intended to serve