Recent scholarship highlights the wealth of varied and interconnected opportunities for learning science that informal environments can provide; yet, participants with different experiences, knowledge, and backgrounds do not all learn in the same ways. Thus, studies are needed that examine how particular participants take up learning opportunities (LOs) in informal contexts. In this ethnographic case study, we focus on the learning experiences of one fifth-grade girl, Nina, who reported that she was not able to learn as much as she had hoped from her participation in an afterschool robotics engineering club. Through analysis of video-recordings, interviews, and field notes, we investigated how instructors and peers shaped LOs for Nina and the environmental tensions that affected how LOs were shaped and how Nina took them up. Comparison of examples in which instructor and peer-afforded LOs were realized and unrealized (i.e., presented in ways that Nina could take them up or not) illuminates multiple tensions. Club members faced tensions related to differing goals and abilities to teach each other, while the instructors faced tensions related to their roles in informal learning environments and their propensity to direct participants to other resources. As a result, many potential LOs for Nina in this rich inquiry learning environment where unrealized because instructors and peers did not shape them in ways that were explicit, elaborated upon, or connected to Nina's prior knowledge, and because Nina was not necessarily attuned to potential LOs in the informal context. We conclude with implications for instructors in informal learning environments.