The COVID-19 pandemic has arguably been one of the most consequential public health events of the modern era, claiming the lives of millions of people worldwide and creating extensive economic, social, and political disruptions. The public and private education sector was particularly impacted, with schools closing their doors and shifting to entirely remote and hybrid models during the height of the pandemic. Emerging research on the impacts of school related closures and remote teaching practices focused predominantly on the initial stages of pandemic response during the Spring of 2020, largely within higher education settings. This study analyzed archival survey data from a suburban school district in Massachusetts, to explore the effects of the COVID-19 pandemic on K-12 teachers and students across three distinct phases of the pandemic: Phase 1 (March 2020-June 2020), Phase 2 (September 2020-April 2021), and Phase 3 (April 2021-June 2021). Educators reflected on their experiences related to four primary factors: (1) preparedness/professional development, (2) technological pedagogical knowledge (TPK) and self-efficacy, (3) professional impact, and (4) personal impact. Differences between grade level educators (primary and secondary) and phases of the pandemic were also explored. Student data was analyzed from two surveys completed by high school students in December 2020 and in May 2021. Educators consistently cited a lack of preparation/professional development and support, as well as heightened levels of chronic stress and indications of burnout (e.g., low motivation, fatigue, decreased work-life balance) throughout each phase. Hybrid models of instruction during phase 2 presented the most significant challenges for educators. Grade-level differences were observed during each phase in educator preparedness, TPK, and personal impact. Phase-level differences were also observed for educator preparedness, TPK, and professional impact. Students in this study reported some of the challenges of remote/hybrid learning as feeling disengaged from teachers and peers, difficulty concentrating and retaining new information, technology issues, and the need for more flexibility and breaks throughout the day. By contrast, some students felt that remote or hybrid instruction increased flexibility for engaging in school, through the use of digital learning platforms and being able to participate in a more relaxed, comfortable home environment. Implications for future research are considered, as well as practical applications of research in this area on educational leadership. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]