Background: Existing research suggests that one of the challenges for teachers in persisting with innovative inquiry curricula is their difficulty scaffolding students' transitions into technology-supported and open-ended activities. The question of whether students can effectively scaffold one another's transitions has not been previously investigated, in part, we argue, because of a predominant focus in collaborative learning research on short-term tasks and perfunctory "helping" behaviors. Purpose: This article addresses the nature and role of students' collaborations in learning through design, a technology-rich science inquiry curriculum. Within this environment, we examined emergent collaborative patterns among students, the affordances of those patterns for effective learning, and students' reflections on their interactions. We paid particular attention to how students with varying degrees of previous experience in this curricular approach collaborated with one another. Setting: This study took place at a university-affiliated elementary school in a West Coast urban area. Population: Two mixed-grade classes of fourth- and fifth-grade students (n = 63) and their science teacher participated in this study. Fifth-grade students in one class had extensive experiences with learning through design during the previous year. Practice: For 10 weeks during the fall, students in both classes learned about marine biology. During this time, they also worked in teams to create marine simulations using Logo Microworlds programming and multimedia software. Research Design/Data Collection and Analysis: Design-based research guided the creation of the curriculum and examination of its effectiveness. Ethnographic methods, grounded theory, hermeneutics, and discourse analysis were used to collect and analyze video of student collaborations and interviews. Analysis of variance was conducted using the coded results from student interviews to determine significant differences among groups. Results: We found that experienced fifth graders took on many socializing functions, effectively apprenticing younger students into the practices of learning through design. Interviews revealed that both fourth-grade and fifth-grade students were highly reflective about their respective collaborative roles and that experienced students benefited as much as, if not more so, than inexperienced students from this arrangement. Conclusions: Given experienced students' strategic, effective, and thoughtful ongoing collaborations with their fourth-grade counterparts, we introduce and propose the term peer pedagogy to describe these interactions. This term and our constituent results have implications for existing research and practice in collaborative learning and project-based technology-integrated curricula as well as for theory and scholarship on children's roles within learning communities.