In response to the COVID-19 pandemic, most elementary and secondary schools and local educational agencies (LEAs) across the United States stopped offering in-person instruction in February or March 2020. By the middle of April 2020, 48 states, four U.S. territories, the District of Columbia, and the Department of Defense Education Activity ordered or recommended school building closures for the rest of their academic year, affecting at least 50.8 million public school students. Congress has expressed interest in the impact of the pandemic on elementary and secondary schools, especially states' and LEAs' ability to successfully transition to remote learning, as well as the extent to which schools have implemented returns to in-person learning. This report focuses on online learning in elementary and secondary schools during the COVID-19 pandemic and on the most emergent issues associated with the implementation of online learning on a mass scale that took place at the start of the pandemic in spring 2020. It also describes the issues faced by school districts as they consider approaches for providing instruction in the 2021-2022 school year. Finally, it delineates federal efforts to provide assistance to support states and localities dealing with these issues.