Journal of Engineering Education

Background: Given the growing need for a well-prepared engineering workforce, strategic investments must extend beyond formal education to include nonformal learning environments.While prior research highlights the role of parents, educators, and mentors in shaping young children's engineering development, siblings remain an understudied yet influential force.Purpose: This study examined older siblings' roles when interacting with their younger siblings on engineering design tasks within two nonformal learning environments-home and an afterschool program.These interactions occurred during naturalistic environments, void of adult guidance and presence.Methods: Using a naturalistic exploratory approach, we examined the interactions of six sibling pairs.We collected and analyzed approximately 13 h of video across the two nonformal learning environments.Results: Siblings enact a variety of interaction strategies and roles that shape joint engagement in engineering practices differently.While some roles overlapped with those in the literature, we observed roles unique to siblings and young learners.The most frequent roles observed were colleague/peer, lead engineer, and provocateur.However, even rare roles and interaction strategies were found to support engineering practices.Conclusion: This study highlights the potential of sibling interactions as a meaningful component of engineering learning; integrating engineering activities for siblings could leverage natural social and learning relationships to support siblings' development and growth as engineers.