Various theoretical models have been used to study the development of the base ten system in fields of study that were at times, very different. This study is the first step in testing one of these theoretical models, the "UDSSI Triad Model" (Fuson et alii(1997); Fuson, Smith & Lo Cicero (1997)), a model that suggests a linear development of four successive concepts children build while learning the base ten system. In order to characterize the different successive concepts, we defined "translation links" and "structure links", which take place among the three ways of representing numbers : oral-verbal representation, decimal representation written in numbers and quantitative representation. One hundred-twenty-one Belgian francophone children in grades 2 and 3 were tested individually. The quantitative analyses made on the results partially confirmed our distinction between translation and structure links. In general, they allow us to question developmental order and the different concepts suggested in the model.