These are the appendixes for the full report, "Changes in School Climate during COVID-19 in a Sample of Pennsylvania Schools." The REL study analyzed changes in scores from a pre-pandemic year (2018/19) to the 2020/21 and 2021/22 school years, both of which were affected by COVID-19 and related policy changes. These technical appendixes are meant to supplement the slideshow to provide extended detail on the methods and analyses used to answer the study's research questions. Appendixes: (1) Data and methods; (2) Supporting analysis; and (3) Nonresponsive bias analysis. [For the full report, see ED629789.]