Background: Classroom physical activity (PA) breaks offers a way for schools to increase children's PA, improve time on-task, and improve academic scores. Professional development delivery models, technology infrastructure, and opportunities for collaboration are influenced by school district size. These factors may impact teachers' perceptions of instructional issues, including PA. However, little is known on how the size of school districts may impact teachers' perceptions of classroom PA. Purpose: The purpose of this study was to explore if teachers' perceptions of classroom PA vary based on district size. Method: Sixty teachers from five school districts (1 large public, 3 medium (2 public, 1 private), and 1 small public) took part in a semi-structured interview. Data were analysed through the process of immersion/crystallization. Results: There were a few key differences between districts. The largest district more often reported integrating PA into reading and writing while all other districts most often incorporated PA into math. Additionally, the largest district more often incorporated classroom PA 1-2 times/day while other districts more frequently reported utilizing PA 3+ times/day. The medium-sized public districts were most likely to incorporate classroom PA during transitions between subjects and to utilize online video resources (e.g., GoNoodle) compared to other districts who were more likely to incorporate PA during instruction and incorporated more general movement (e.g., stretching). Interestingly, the smallest district reported the least amount of teacher collaboration in regards to discussing classroom PA with their colleagues. Conclusion: Results provide evidence that teachers have positive view of classroom PA but there are differences on teachers' perfactions