The project for the teaching of elements of Probability and Statistics at the ages 11 - 14 which I intend to describe is the result of the work of the Didactic Research Group of Pavia (1), formed of 5 university researchers and about 20 in-service teachers. In this paper I will refer in particular to the Mathematical contents of our proposal. But in order to reach a good understanding of the proposed work I should like to stress that the classroom activity we propose should include these very important steps: the presentation of a problematic situation, the intuition and explanation of one or more solutions, the collective discussion, the generalization and sometimes the formalization of the results and finally, if it is possible, their use in interesting real-life applications.