Instructional practices in science education often create dichotomies of "expert" and "outsider" that produce distinct power differences in classrooms. Building upon the idea of "making present practice" to disrupt these binaries, this paper presents select findings from a year-long study investigating two urban teachers' use of community-based science (CBS) instructional practices to create relational shifts that reframe expert and expertise in science instruction. By examining how CBS instructional practices reframe power through co-learning experiences, our findings demonstrated that teachers positioned youth as knowledge constructors through three instructional practices: (a) creating space for students to share their knowledge and experiences, (b) positioning students' lives and experiences as assets to/within science, and (c) being responsive to assets in future lessons. We use these findings to demonstrate how CBS instructional practices support shifts in relational dynamics by creating spaces of rightful presence, where students are viewed as legitimate classroom members who contribute scientific knowledge in practice and have power in the classroom space. By relinquishing traditional boundaries in science teaching to deconstruct ideas of who holds power, we position CBS instructional practices as a means to expand educational equity by legitimizing students' diverse sensemaking and re-mediating hierarchical structures in classroom spaces.