Abstract
<jats:p>This chapter reports on observations of first-grade students’ mathematical argumentation while solving a rich mathematical task in groups of three to four students. Observations originate from a powerful classroom setting, emphasising cognitive complexity and teaching for robust understanding. The study aims to examine how students articulate their solutions and to determine whether levels of argumentation may help teachers identify potentially gifted students in a heterogeneous classroom. Teacher identification is important for guiding and designing adapted teaching, especially for gifted students in Norway, which lacks a dedicated gifted education system. The study employs Toulmin’s simplified model of argumentation and demonstrates how young students (ages six to seven years) solve a specific, rich mathematical task. The unconventional task had four different phases and questions with multiple or no answers. Findings confirm some previously identified gifted students and identify one additional student. The chapter concludes with implications and recommendations for teachers.</jats:p>