In this workshop, the participants play with an array of numbers considered by the German mathematician G. W. Leibniz in the beginning of the XVIII century. This array of rational numbers is mathematically very rich and its investigation will be the main topic of the workshop. This richness consists of multiple possibilities of looking for patterns, formulation of conjectures, searching for
analogies and making connections. This may constitute a genuine mathematical investigation that introduces young students to the need of using variables to describe mathematical patterns and to the different roles played by proofs in the mathematical endeavour. The idea of series will also be discussed and the purpose of Leibniz’s work on this array will also be analyzed.

This workshop illustrates a concrete way of adding an historical dimension to the teaching of mathematics, especially when looking for significant tasks for young learners.