This paper focuses on students’ mathematical discourse emerging from interactions in the digital environment GeoGebra, in which one can construct virtual objects that realize mathematical signifiers and then interact with them. These virtual object realizations can become dynamic interactive mediators (DIMs) that influence the development of the learners’ mathematical discourse. In this case study, I analyze in fine detail the discourse developed by two dyads of students in response to an unfamiliar interview question. One dyad came from a class in which GeoGebra was not part of classroom practice and included students who, according to the teacher’s evaluation, were standard-to-high achieving. The other dyad was from a generally demotivated and low-achieving class in which GeoGebra had become part of classroom practice. The analyses, focused especially on the low-achieving dyad, are guided by the question of how DIMs shaped these students’ discourse. According to the analysis, these students ended up succeeding where standard-to-high-achieving peers did not. Moreover, the detailed analysis of the ways in which the DIMs supported this dyad’s learning showed mechanisms that may be general rather than specific to this one case. This suggests that appropriate integration of DIMs into the teaching and learning of high school algebra can be beneficial for low-achieving students.

本文重点研究在数字环境GeoGebra中交互作用产生的学生数学话语，其中可以构造实现数学符号的虚拟对象，然后与它们进行交互。这些虚拟对象的实现可以成为动态的交互式中介者（DIM）会影响学习者数学语篇的发展。在本案例研究中，我将详细分析两个双子系学生针对一个陌生的面试问题所发展的话语。一个双胞胎来自一个课堂，其中GeoGebra不属于课堂实践，并且根据老师的评估，其中包括达到标准至高成就的学生。另一个二元组来自于普遍动力不足且成绩不佳的班级，其中GeoGebra已成为课堂练习的一部分。这些分析（尤其是针对成绩不佳的二分法）的重点是DIM如何影响这些学生的话语。根据分析，这些学生最终取得了成功，而标准至高成就的同学则没有。此外，对DIM支持这种对偶学习的方式的详细分析显示，该机制可能是通用的，而不是特定于此情况的。这表明，将DIM适当集成到高中代数的教学中可能对成绩不佳的学生有利。