Discipline-based education research (DBER) uses researchers' disciplinary background to inform investigations into university teaching and learning. The terms of student involvement in DBER are often dictated by the researchers, with student choice limited to whether or not they will contribute data. This is counter to the ethos of active student participation in which students can directly influence their university studies. While examples of DBER projects with students as collaborators rather than as informants or subjects exist, such opportunities are usually available to a few students. This paper explores where, why, and how students could contribute to DBER projects by exploring different roles students can take and examining the possibilities for student input to the process of educational research when viewed as an investigative cycle. This identifies places where students can influence research work while being able to disengage as necessary. Going beyond individual students, whole-class contributions also appear practical, opening up the possibility to "co-create DBER."