The Mathematization Process as Object-oriented Actions of a Modelling Activity System

In this paper, we describe and characterize the mathematization process that happened in an open mathematical modelling project, in which all decisions, from the choice of a real-world problem to its solution, were taken collectively by a group of students and researchers. The study was developed according to a qualitative methodological approach. Based on modelling in mathematics education studies and on the Cultural-Historical Activity Theory (CHAT), we could interpret the mathematization process as a set of actions oriented to the activity system object, and the modelling project objective as the activity object itself. We concluded that the mathematization process, permeated by tensions, took place concurrently with the delimitation of the modelling project objective, which caused a series of advances and setbacks in the subjects' actions.