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INTRODUCING THE STUDY OF RANDOM SITUATIONS AND THEIR MODEL BUILDING PROCESS TO 14-15 YEARS OLD STUDENTS

INTRODUCTION The main of this article is to discuss about introduction to probabilities with 14-15 years old pupils. Some research on their probabilistic thinking shows that, depending on the context, some of the spontaneous conceptions they have constitute obstacles to the building of the relationship between probability and randomness. Consequently, these conceptions constitute obstacles to the learning process of probability. We understand here as obstacle a knowledge that is mobilized outside of its domain of validity (Brousseau, 1997). Among others, we can invoke the research of Maury (1986), Coutinho (1994), Coutinho et al. (1996) and Cañizares (1997). Those researches identify some of the misconceptions that, resisting the application of a didactic sequence, become obstacles the construction of the concept of probabilities. Some of these obstacles, particularly the "idea of equiprobability", become more resistant with the age (Fischbein). Consequently, many works in didactics of probability converge to an anticipation of a first contact with the random one and the calculation of probabilities. Beyond the research on conceptions and pre-conceptions of students on probability, we also find some researches about the construction of this concept. Particularly, on the construction of the relation between the calculation of a probability and the probabilistic model that justifies this calculation. Among others, we invoke the research of Zaki (1990), Girard and Parzysz (1998), as well as diverse publications of the Inter-IREM Commission of Probability and Statistics. In this article we will focalize especially the didactic conditions that allow an anticipation of a first contact with probabilities, leading in account the construction of the meaning of relation between calculation and probabilistic model justifying it.