Language in argumentation and solution of problems with graphs

The paper reports an investigation about undergraduates' argumentations to justify answers to elementary calculus problems involving the recognition of relationships among graphs, verbal texts and formulas. The examination of the texts produced over more than ten years highlights serious language difficulties and suggests that we cannot exclude that language is a key factor for the quality of arguments. The main goal of this study is to gain a better understanding of how language difficulties (depending on both competence and attitudes) affect argumentations.