In this study we focus on the design of a digital environment aimed at mediating a collective asynchronous mathematical discussion. According to the design-based research approach (Cobb et al., 2003), we discuss the design of a digital environment with respect to students’ participation and collaborative interactions and teacher’s interventions, by referring respectively to a framework to analyse the collaborative processes realised within computer-supported learning environments (Weinberger & Fischer, 2006) and a framework aimed at characterising the teacher’s roles in orchestrating mathematical discussions (Cusi & Malara, 2013). The results of this analysis provided us with significant insights that suggest both elements for a re-design of the digital environment and new directions for further research to be developed on the role of the teacher in orchestrating asynchronous mathematical discussions within digital environments.