The Project in Hawaii’s Intertidal (OPIHI) is a network of schools and scientist volunteers engaged in the widespread, systematic monitoring of Hawaii’s rocky intertidal zones. OPIHI originated through a partnership funded by the National Science Foundation’s Graduate Fellowships in K–12 Teaching program. This initial partnership developed a thematic framework to allow students to conduct investigations about intertidal organisms and ecology while collecting useful scientific data. This framework became OPIHI. In this chapter, the authors summarize the ideas behind OPIHI, describe the original model of investigation, and examine how OPIHI has been used by different groups to answer a range of student questions, all while maintaining the original thematic focus on intertidal ecology and authentic scientific investigation.