Abstract
Some problem situations are proposed to classes of children aged 8-10, in order to induce the pupils to construct numbers, more specifically decimal numbers. The behaviour of the children is described. An acute observations, performed at the level of the class on a long period (several months and for some children from age 6 to 11 ) gives a ligth to the implicit scientific situation, though at an elementary level. These models are described in axiomatic form.
