ITE has been criticised for being disconnected, with different languages being spoken in the two learning arenas of campus and schools. Bringing people together, such as through formal university-school partnerships, is not enough to open up communicative learning spaces -- sites of collaborative learning that are democratic, safe and supportive. Practicum is recognised as a capstone experience in teacher education in which the mentor's role is crucial. However, there are significant variations in the types and quality of mentoring and only some supportive frameworks. This paper investigates what arrangements are needed to enable mentoring practices as communicative learning spaces. An intervention was designed that structured conversations between student teachers, school-based mentor teachers and university-based teacher educators around an observation-grounded mentoring framework (OMF). Data was gathered from completed worksheets, reflection logs, and interviews and analysed through the lens of practice architectures. We explore issues of knowledge and power in the facilitation of learning when university-based teacher educators visit the school, and classroom observations frame the mentoring conversations. Findings show that the OMF offered a shared language for tripartite mentoring conversations as communicative learning spaces. The paper contributes to knowledge about supportive mentoring practices in ITE.