The COVID-19 pandemic necessitated teachers and students to adopt and adapt to online learning (OL) in a matter of days. The unfortunate school closure situation placed researchers in a remarkable position. This survey-based descriptive study investigated the experiences of teachers in the United States, including an analysis that factors in teachers' existing knowledge of Universal Design for Learning (UDL). Specifically, this study focused on student and teachers (dis-)engagement in learning during the pandemic teaching by examining teachers' instructional challenges and teachers' observations of student barriers to learning, and changes that occurred within these areas between spring 2020 and fall 2020. The findings, combining descriptive quantitative and qualitative data, present similarities and differences in teachers' and students' observed experiences depending on the level of training in Universal Design for Learning prior to the pandemic. The discussion offers implications for future areas of research in engaging OL.