In 2020, the COVID-19 pandemic forced colleges and universities to suddenly transition to a mostly-to-fully online teaching format. Given the nature of the transition and general reservations about online instruction, many were concerned educational quality and achievement would be compromised by large margins. We sought to determine what course design features, if any, helped support undergraduate educational achievement during a sudden transition to 100% online instruction. We addressed our research aim using adapted principles for reflexive thematic analysis, the discernment of ways to interpret data using diverse perspectives and the critique of assumptions (RWJ Foundation, 2008). Following instructor request (JDT), two undergraduate teaching assistants (CEH, JDS) independently discerned design feature quality, instructor assumptions, and student response to features (i.e., anonymous feedback,participation patterns). Analysis was applied to one asynchronous upper-division, general education, writing-intensive kinesiology course (38 enrolled students, 2020 Spring Term). A reiterative process was used, with undergraduate teaching assistants making comparisons to their experience completing the course in-person the previous term (Winter 2020). Five design features evidently helped to support educational achievement during the sudden transition to 100% online instruction: discussion boards, summary slides, reminder emails/slides, video lectures, and posted lecture slides. Students valued the “constant stream” of communication and opportunity to self-pace. Discussion boards incentivized content application and promoted appreciation of peers’ viewpoints, both of which helped with learning and writing-to-learn.The five design features, in combination, provided high fidelity with in-person instruction. We will discuss our findings, limitations of our study, and potential ways to improve the design of online courses based on our results