The COVID-19 pandemic profoundly impacted the methods of instruction for K12 and higher education institutions around the world. Schools and families were challenged to adapt to online-based modes of instruction with minimal preparation. This study examined the importance of the learning environment and commitment to assignments as predictors of the academic performance of junior high students during the COVID-19 pandemic. We obtained data from 328 seventh through ninth grade students enrolled in an urban school district in the Delta region of Arkansas. Students used the same online learning platform, Lincoln Learning Solutions, receiving instruction in virtual, mixed, or on-site learning environments. We examined the total time spent in each course, overall assignment completion, and average grades for science, mathematics, and ELA. Our results show that when we considered only the learning environment, students in the on-site environment consistently outperformed their peers in the virtual learning environment across all subjects and grade levels, except for mathematics at the eighth-grade level. However, when we also considered students' online assignment behaviors (time spent working on assignments, and number of assignments completed), there was a significant improvement in the prediction of academic performance for mathematics in the seventh and ninth grade, for science at the eighth-grade level, and for ELA at the ninth-grade level.