Number system and computation with a duo of artefacts: the pascaline and the e-pascaline

We are using a duo of artifacts, constituted by a mechanical arithmetic machine and its digital counterpart, to enable six-year old French students to learn about numbers. The experiment shows the separate conceptualization processes involving numbers as sign of a quantity and number sequences on one side and recursive addition, computation and its effect on the decimal code for numbers on the other side. The duo of artifacts enabled the design of situations that required these processes to be connected. We observed how students and teachers used the duo and discuss the results concerning the conceptualization of number.