In this study, we aim to investigate the role of language in small group peer collaboration. Based on the notion of symmetrical scaffolding, we draw on theories of dialogic space and functional linguistics to analyse a transcript of three six-year-old students as they explore a shared understanding of 'two more than'. Using Martin and White's (2005) engagement framework as an analytical tool, we identify how the three students used language resources in contractive and expansive ways to move each other's learning forward. These findings provide a perspective of symmetrical scaffolding closely focused on students' language choices that support engagement with each other's thinking. We suggest that a focus on use of language with young students is valuable in identifying the type of mathematical discourse that will support peer collaboration in problem solving and mathematical reasoning.