A Professional Development Model for Training Biology GTAs in Equitable Teaching: Implementation and Evaluation at...

Graduate Teaching Assistants (GTAs) play a critical role in undergraduate biology education, yet rarely receive training in the inclusive teaching practices that support student belonging, growth mindset, and persistence in STEM. Many GTAs are future faculty, department chairs, and course designers, and investing in their development early represents an opportunity to improve undergraduate experiences at scale. Here we describe the SEP-GTA professional development model, adapted from the Student Experience Project (SEP) for university faculty, and its implementation at two minority-serving research universities. The model is founded around three pillars: a GTA community of practice with peers, evidence-based inclusive teaching practices rooted in growth mindset and belonging research, and collection of formative feedback from students. We present program evaluation data showing that after participating in the program, GTAs had higher endorsement of growth mindset beliefs (ranging from +5% to +11% across items), greater familiarity (+16%) and comfort with (+12%) using evidence-based teaching practices, increased interest in professional development (+18%), and greater perception of departmental support (+11%). After the training, 13 of the 16 specific teaching strategies were used by more than 80% of GTAs in their introductory biology laboratory and lecture courses. The SEP-GTA resources are freely available and flexible enough to be adapted across institutional contexts, making this model a practical starting point for institutions looking to invest in GTA professional development and build learning environments where all students feel they belong and can succeed.