This text and the oral presentation that we will make of it is intended to be the concrete answer to those who think that we cannot “do” mathematics in kindergarten. Our experience, based above mainly thanks to the professionalism of our fellow teachers in this school level, shows, on the contrary, that children aged between 3 and 6 are very interested in mathematics, naturally suitable for their age, a mathematics that we have called “naïve”, that is, without formalism.