THE NUMBER LINE AS A REPRESENTATION OF DECIMAL NUMBERS: A RESEARCH WITH SIXTH GRADE STUDENTS

Based on Janvier’s (1987) model on representations, in this paper we examine 12 year old students ’ understanding of the concept of decimal numbers. For this reason the study was conducted with the use of three kinds of tests related to decimal numbers. These three tests involved recognition, representation and translation tasks. In particular, the idea of the number line as a geometrical model is being discussed in respect to representations and translation between different representations. The application of the implicative statistical method demonstrated a compartmentalization of the different tasks and this signifies that there is a lack of coordination between recognition, representation and translation in decimal numbers