Résumé
Mathematical learning disability is characterized by specific impairment of arithmetic performance, which would be explained either by number sense deficit (analog magnitude representation), or by a limited access to this magnitude via auditory verbal word frame or visual arabic number form. The aim of this study was to determine whether an intensive, short and individualized intervention based on arabic number placement and calculation on external number line would improve not only the link between the analog code and the arabic code, the analogical code itself, but also calculation in children aged 9 to 13 years with mathematical learning disability. The intervention was carried out with four children, aged 9 to 12, in three 30 minutes sessions per week, for four weeks, using DeCaLigne software. Five tests were carried out with each of them in order to quantify their performance: one month before the intervention, just before the beginning of the intervention, just after the end of the intervention, one month after the end of the intervention and five months after the end of the intervention. The mental number line, number line calculation, analog code, but also the relationship between analog and arabic codes, mental calculation and arithmetic facts were thus assessed several times to determine the specificity, generalizability and maintenance of the effects of the intervention. Results showed that participants improved their numerical acuity and thus were able to increase their performance in placing arabic numbers on an external number line. The implementation of visual strategies based on quartering as well as outcome estimations were favorable to the development of their mental number line accuracy but also to the increase of their speed of execution in the proposed tasks. Additional sessions would be needed for some participants to automate these new procedures. Nevertheless, little generalization could be observed, which does not allow to affirm a direct link between the improvement of the approximate number system and other mathematical skills. The satisfaction derived from this intervention by the participants, as well as, the real progress felt by them, nevertheless allows us to consider its implementation in speech therapy clinical practice.