Purpose: The purpose of this study is to examine how dialogic spaces were co-constituted (opened, broadened and deepened) between students engaged in divergent and convergent collaborative learning tasks, orchestrated by teachers in Finnish primary and secondary schools. The concept of dialogic space refers to a dynamic, shared resource of ideas in dialogue and has come to represent an ideal form of educational interaction, in the contexts of collaborative learning, joint creative work and shared knowledge-building. Design/methodology/approach: A socio-cultural discourse analysis of video-observed classroom dialogue, entailing the development of a new analytic typology, was undertaken to explore the co-constitution of dialogic space. The data are derived from two qualitative studies, one examining dialogue to co-create fictive video stories in primary-school classrooms (divergent task), the other investigating collaborative knowledge building in secondary-school health education (convergent task). Findings: Dialogic spaces were opened through group settings and by the students' selection of topics. In the divergent task, the broadening of dialogic space derived from the heterogeneous group settings, whereas in the convergent task, from the multiple and various information sources involved. As regards the deepening of dialogic space, explicit reflective talk remained scarce; instead the norms deriving from the school-context tasks and requirements guided the group dialogue. Originality/value: This study lays the groundwork for subsequent research regarding the orchestration of dialogic space in divergent and convergent tasks by offering a typology to operationalise dialogic space for further, more systematic, comparisons and aiding the understandings of the processes implicated in intercreating and interthinking. This in turn is of significance for the development of dialogic pedagogies.