Over the last two decades, online learning adoption happened gradually in K-12 schools, mostly among innovators and early adopters. Then in 2020, the onset of COVID-19 ignited widespread adoption of emergency online learning, practically overnight. Online learning moved swiftly from the periphery to the core of K-12 education since it offered the most practical way to keep students learning while school buildings were closed. Beginning in the fall of 2020, the Christensen Institute undertook a two-year series of nationally representative surveys to make sense of online learning adoption and practice at this remarkable juncture. By now, American students have experienced over a year of pandemic schooling. What role has online learning played during that period? How will the pandemic impact online learning adoption and practice in the future? And what should education leaders do to ensure that online learning, where it takes root, ushers in a more student-centered future? This report shares insights from the most recent round of surveys, which collected responses from 872 K-12 administrators (representing 841 districts from 49 states plus the District of Columbia) and 1,042 K-12 teachers (representing 821 schools from 48 states plus the District of Columbia) in April and May of 2021. Follow-up interviews were also conducted with 15 survey respondents to get a more nuanced understanding of their teaching arrangements and experiences over the course of the year. Part 1 of the report describes what instruction looked like for teachers and across school systems during the 2020-21 school year. Part 2, shares what survey respondents reported about their future plans for online learning and online-enabled instructional models. Part 3, makes sense of the trends that surfaced in the survey data and offer insights for steering pandemic-induced emergency online learning toward student-centered learning across K-12 education. [The research underlying this report was conducted in partnership with Bay View Analytics. Additional funding for the report and the associated survey was provided by the Jaquelin Hume Foundation and Stride.]