Efforts to improve learning outcomes in undergraduate mathematics are backed by calls for instructors to move away from persistent pedagogical norms, such as traditional "chalk-talk lectures" and timed closed-book exams. Although the movement towards active learning pedagogies and alternative assessments is gaining ground, uptake has been slow. But when traditional practices became virtually impossible to maintain during the coronavirus pandemic, many instructors quickly gave up old methods for new ones. This qualitative study sheds light on how twenty-eight instructors of undergraduate mathematics experienced teaching through the coronavirus pandemic. It documents stories they told to describe their experiences and explores how they adjusted their teaching practices. A purposeful sample of instructors whose teaching experience spans 58.5 years participated in the study. They taught lower- and upper-division courses during the pandemic and came from colleges and universities across the United States. The primary data collection method was semi-structured interviews. Four salient storylines emerged from data: (1) Remembering other times of change and disruption, (2) Pivoting to emergency online instruction, (3) "Like flying blind:" navigating a new normal, and (4) Coping. In addition, analysis of participants' stories revealed that they adjusted five dimensions of practice for teaching during the pandemic: (1) Representing Mathematical Content, (2) Choosing Tasks and Content, (3) Monitoring: "Leaning Over Their Shoulders," (4) Building a Community of Mathematics Learners and Doers, (5) Assessing for Learning During the Pandemic. The lessons we learn from this emergency will be "educative" for this crisis and the next. Moreover, the coronavirus pandemic also offers an opportunity to examine longstanding norms in undergraduate mathematics education. This study offers recommendations for practitioners, leadership, and further research. [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.]