Students’ mental health has been an increased concern since the outbreak of the COVID-19 pandemic. However, academic outcomes have received very little attention. In this study, changes in students’ achievement motivation are investigated using an expectancy–value framework. Participants (n = 90) were high school students (grades 9 and 10) who reported on their expectancy and value perceptions in regard to learning before and during the pandemic (i.e., January and November 2020). Changes over time and as a function of extraversion/introversion were analyzed using repeated measures multivariate analyses of variance (MANOVAs). Most perceptions were found to be stable with the exception of interest in learning, which increased as a function of extraversion. Results are discussed in light of relevant pre-pandemic evidence.