Despite evidence regarding the ineffectiveness of ability grouping practices in benefiting all students (Francis et al., 2017), grouping students by attainment level remains a persistent organisational approach in many primary school mathematics classrooms. This presentation will focus on a section of a comparative, multiple case study drawn from a larger doctoral research project that investigated the ways in which targeted professional learning can influence the beliefs and pedagogical practices of primary school mathematics teachers in ability-grouped classrooms. This session will draw on the experiences of two primary school teachers, one who taught the lowest ability mathematics group and the other who taught the highest ability mathematics group. Findings of this study showed that a nurturing environment was evident in both the lowest and highest ability group where teachers exerted a higher level of control through teacher-centred practices. In both cases, the teacher worked to ‘save’ their students from learning that was perceived as too difficult (lowest group) and from making any careless errors (highest group). These findings have implications for teachers and school leaders as the nurturing environments that evolved from ability grouping in this study were shown to impede the implementation of effective teaching practices in the mathematics classroom.