Grappling with uncertainty is an essential element of students' science learning and sense-making processes, yet literature is limited regarding how teachers can facilitate and use student scientific uncertainty as a pedagogical resource in their classrooms. Furthermore, progress on pedagogical practice depends on both the ability to notice one's perceptions and engage in opportunities to experience and reflect on new instructional approaches. To date, there are few professional development experiences explored in literature that explicitly aim to enhance teachers' awareness and pedagogical practice regarding the use and facilitation of student scientific uncertainty. As such, this qualitative study follows a group of 11 middle school science teachers before and after participating in a week-long practice-based professional development (P-BPD) specifically designed to foster teachers' ability to use student uncertainty as a pedagogical resource. Interviews were conducted and analyzed prior to the P-BPD, immediately after the P-BPD, and the year following to measure shifts in perceptions over time. Additionally, classroom practice was observed both before and the year following the P-BPD. Overall, we found that teachers' awareness of how to use student scientific uncertainty grew both in their expressed perceptions and in their observed classroom enactment. After engaging in the P-BPD, many teachers expressed an enhanced awareness of the productive potential uncertainty can have, as well as increased understanding of potential sources and responses to student uncertainty. Additionally, in the post-implementation observations, most of the teachers demonstrated more diverse use of uncertainty navigation strategies, intentionally raising, maintaining, and reducing scientific uncertainty more often. Teachers were observed using student ideas and uncertainties to drive the trajectory of their lessons more consistently. Notably, we report counterexamples for teachers who demonstrated less or no shifts in perceptions or practice. Furthermore, teachers explicitly identified experiences from the P-BPD that fostered shifts in both their perceptions and practice.