In March of 2020, in response to the onset of the COVID-19 pandemic, the state of Illinois mandated the transition to remote instruction for all schools. Although schools had the option to resume in-person instruction during the 2020-21 school year (SY21), the Illinois State Board of Education (ISBE) acknowledged that in-person instruction may not be safe or feasible for all schools and all students. In turn, districts and schools made decisions, conditional on the contexts of their schools and communities, to return to in-person instruction, remain in remote instruction, or employ a combination of in-person and remote instruction over the course of the SY21 (ISBE, 2020). Additionally, students and caregivers in schools that offered in-person instruction often had a choice to attend in-person or continue learning remotely. In this report, the first in the Learning During the Pandemic in Illinois series, we ask: What were the patterns in instructional modality throughout the SY21, and how did those patterns relate to school characteristics? The second report describes the relationship between modality in schools and school average test scores in English Language Arts (ELA) and math. The third report examines how in-person attendance at the student level contributed to student learning. In the current study, we grouped schools into four pathways based on movements across instructional modalities at four key time points: September 2020, December 2020, February 2021, and April 2021. These pathways varied in the amount of in-person instruction students received over the course of the year, ranging from substantially in-person to entirely remote across all four time points. We uncovered important differences in school characteristics across modality pathways. [For Part 2, see ED624503. For Part 3, see ED624504.]