One of the most critical factors for improving the quality of instruction provided by classroom educators is teacher professional development. However, the recent COVID-19 pandemic and shift to virtual instruction impacted how teachers access and engage in professional development as well as how teacher trainers support new learning. The present research analyzed the association of reading comprehension practice-based professional development (PBPD) provided in a virtual setting during the COVID-19 pandemic with the changes in teachers' understanding of using top-level structures to support reading comprehension. We used latent transition analysis to analyze the pre- and posttest scores of teachers (N = 409) participating in a 2-day web-based PBPD, which combined synchronous and asynchronous instruction through a Massively Open Online Virtual (MOOV) learning platform. We identified three classes of teachers: Poor Overall Understanding of top-level structure, Poor Understanding of Organization and Solution, and Good Overall Understanding of top-level structure. Transitioning from a class with Poor Overall Understanding at the pretest to a class with a deeper understanding at the posttest was associated with those participants who had better scores on asynchronous MOOV activities choreographed to support synchronous instruction. We discuss implications for future research and teacher training, especially those provided in a virtual environment.