Background: In this paper, we extend theories of group cognition and regulation to examine how regulation occurs as part of a learning ecosystem. We examine our instructional approach, Embedded Design, that uses Human-Computer Interaction (HCI) as a conduit for students to make sense of their sociotechnical world and the ways people design everyday interaction around technology. Methods: Our research questions centered on identifying (RQ1) the types of problems that require students' collective regulation. Our population included learners aged 8-12 enrolled in a play-based after school HCI design club. Using micro-analytic techniques, we examined the HCI design processes of four teams over nine sessions and four learners over two years. Findings: We identified the most common problems students encountered, how regulation and negotiation played out across different levels of analysis, what types of learning occurred as participants worked to improve collaborative processes over time, and the role that technology played in the process. Contribution: We end the paper by proposing a model of how nested collective knowledge building processes evolve over time and discuss the implications of our findings for K-12 HCI education.