In this study, a temporal analysis and the analytical category of intersubjectivity are used to investigate how teachers and Latino/a bilingual students constructed shared communicative spaces in group mathematical discussions in an after school mathematics program in a culturally, linguistically, and economically diverse primary school. Intersubjectivity refers to the "common ground" or "shared understandings" that participants achieve through dialogue around joint activity, such as solving and discussing mathematical problems. Understanding how participants achieve intersubjectivity in mathematical discussion requires a temporal analysis, which includes attention to how particular instances of intersubjectivity have a history in previous interactions and a future in related activity. Using two illustrative cases, this study traced the histories and futures of the students' shared understandings, or intersubjetivities, across time. Findings highlight the importance of intersubjectivity as a catalyzer of a range of linguistic, cultural, and material resources, including Spanish and English, multiple representations, gestures, revoicing, and inscriptions, to help participants to attune to one another's understandings and further their intersubjectivity. These shared understandings were sometimes facilitated by divergent interpretations or confusions that teachers and students in ethical, emotional, respectful ways managed to address.