There are two purposes to this study. The first was for me, as a teacher, to try something new in my instruction and grow from it. The second purpose of this study focused on the students. I wanted to see what level of performance in problem solving my students are at currently, and how the use of journaling and discourse affected the students' problem solving abilities. A problem-solving unit was taught heuristically in order to introduce students to the various strategies that could be used in problem solving. Math journals were also used for problem solving and reflection. Classroom discourse in discussion of problem solving situations was used as a means of identifying strategies used to solve the problem. Explanations and justifications were then used in writing and discourse to support students' solution and methods. An analytic problem-solving rubric was used to score the problems solved by the students. These scores, along with explanations and justifications, and discourse were used as data and analyzed for common themes. The results of this study demonstrate overall improvement in student performance in problem solving. Heuristic instruction the students received on strategies in problem solving helped to improve their ability to not only select an appropriate strategy, but also implement it. This unit, along with the problem solving prompts solved in the journals, helped to improve the students' performance in explanations. It was discourse combined with all the previous instruction that finally improved student performance in justification.

Plusieurs auteurs se sont intéressés au développement des conduites explicatives et justificatives (CEJ) chez des enfants typiques. La littérature reporte aussi de plus en plus d’études qui s’intéressent aux compétences pragmatiques et interactionnelles des enfants qui présentent un trouble du développement du langage (TDL) en montrant que ces enfants présentent des spécificités par rapport aux enfants typiques. Dans ce travail, nous avons combiné ces deux pistes de réflexion en investiguant les CEJ produites par des enfants avec TDL (5-7 ans) et des enfants typiques (4-7 ans), ainsi que par leurs mères, dans des interactions mères-enfants italophones et francophones dans deux activités différentes : unjeu symbolique et une lecture conjointe d’un livre en images. Nos résultats montrent que les deux langues présentent des patrons similaires. Cependant, des différences ponctuelles liées à la langue ont pu être mises en évidence. Les mères prennent en charge les activités proposées et l’activité paraît influencer le fonctionnement des interactions et la production des CEJ. Les enfants avec TDL présentent de CEJ moins élevés que leurs pairs typiques dans l’activité de jeu symbolique et ils semblent avoir davantage besoin que ces derniers du support de leur mère pour en produire dans l’activité de lecture conjointe (notamment dans le corpus francophone). Les mères des enfants typiques et des enfants avec TDL présentent des comportements globalement similaires en amont mais elles semblent s’adapter aux besoins de leurs enfants en aval. Compte tenu de l’importance sociale et éducative de ces conduites, nos résultats pourraient avoir des implications cliniques / Several authors have studied the development of explanations and justifications(E/J) in typical developing (TD) children. Similarly, it is possible to find in the literature studiesthat analyze pragmatic and interactional skills of children with specific language impairment(SLI). These studies show that children with SLI present specific behaviour when compared toTD children. In this thesis, we merge these two strands of research by investigating E/Jproduced by children with SLI (aged 5-7) and TD children (aged 4-7), and by their mothers. Todo so, we analyzed mother-child interactions (in Italian and French) during two differentactivities: symbolic play and joint wordless picture-book reading. Similar patterns wereobserved in both languages. Nevertheless, specific differences related to the typology of thelanguage were highlighted. Our results show that the management of the activity is globallyasymmetric, but important interindividual differences were observed. Moreover, activities playa central role in shaping the structure of interactions and E/J. Furthermore, children with SLIshow lower rates of E/J than their typical peers in the symbolic play and seem to need thesupport of their mothers more than TD children in the joint reading activity (particularly in theFrench corpus). Finally, the mothers of TD children and children with SLI show somesimilarities in the way they solicit E/J, but at the same time they fine tune their reactions to E/Jproduced by children according to the children’s needs. Given the social and educationalimportance of explanations and justifications, our results may have some clinical implications.