Journal ArticleClassroom Observations Indicate the Positive Impacts of Discipline-Based Professional DevelopmentViskupic, Karen; Ryker, Katherine; Teasdale, Rachel; Manduca, Cathryn; Iverson, Ellen; Farthing, Dori; Bruckner, Monica Z.; McFadden, RoryWe compared 236 geoscience instructors’ histories of professional development (PD) participation with classroom observations using the Reformed Teaching Observation Protocol (RTOP) that describe undergraduate classes as Student-Centered (score ≥ 50), Transitional (score 31–49) or Teacher-Centered (score ≤ 30). Instructors who attended PD (n = 111) have higher average RTOP scores (44.5 vs. 34.2) and are more frequently observed teaching Student-Centered classes (33% vs. 13%) than instructors with no PD (p < 0.001). Instructors who attended PD that is topically-aligned with content taught during the classroom observation are likely to have RTOP scores that are higher by 13.5 points (p < 0.0001), and are 5.6 times more likely to teach a Student-Centered class than instructors without topically-aligned PD. Comparable odds of teaching Student-Centered classes (5.8x) occur for instructors who attended two topical PD events but were observed teaching a different topic. Models suggest that instructors with at least 24 h of PD are significantly more likely to teach a Student-Centered class than instructors with fewer hours. Our results highlight the effectiveness of discipline-specific PD in impacting teaching practices, and the importance of attending more than one such PD event to aid transfer of learning.2019-05-0110122559Journal for STEM Education Research2520-8705https://doi.org/10.1007/s41979-019-00015-w1022844National Science Foundation