School participation in citizen science (SPICES) is a growing practice, especially in science and environmental education. However, the literature shows that the school setting often serves as a diminishing factor in learners’ tendency to frame their learning in the citizen science project expansively, thus decreasing the potential of SPICES to foster their agency and environmental citizenship. The current study sought to explore how flexible design of SPICES curriculum materials may offer opportunities to promote the development of expansive framings among students in various age levels. We did so by analyzing the ways students framed their learning within different implementations of The Bermuda Buttercup Mystery initiative. This SPICES program regarding invasive plant species was designed flexibly to support adaptations required for its incorporation into various school contexts. In-depth group interviews were conducted in three different age-level classes in a multiple case-study approach. Findings indicate that across cases, three main categories of expansive framing emerged: an ambassadorship framing, a “helping the scientist” framing, and an “advancing knowledge” framing. We argue that the expansive framings found are related to different emphases embedded in each implementation, which the flexible design of The Bermuda Buttercup Mystery had enabled.