Due to COVID-19 pandemic restrictions, new instructional designs for mathematics courses have recently been developed. Unlike traditional e-learning courses, distance learning via videoconferencing contains more synchronous elements and is therefore more closely related to classroom instruction. Since theories of person-environment fit suggest that course modality may have an impact on learning processes, this study compares the effectiveness of on-campus (in-person) and synchronous distance tutorials as essential components of a mathematics preparatory course. Using a within-between-subject design, we examined performance gains of first-year student teachers (primary and lower secondary level) during a two-week preparatory course in relation to (1) tutorial variation, (2) students’ prior knowledge, and (3) general and specific affective factors. Overall, our results indicate that preparatory courses with on-campus and distance tutorials can be similarly effective. However, considering students’ prior knowledge as measured by an entrance test, the course variant proved to be a decisive factor for students with higher test scores: While students with lower scores showed comparable performance gains in both on-campus and distance tutorials, students with higher scores increased their mathematics performance only in on-campus tutorials. Furthermore, the results indicate that the impact of affective factors on course performance differs in the two tutorial variants. While students’ self-efficacy and engagement predict learning outcomes in on-campus tutorials, mathematics performance in distance tutorials is positively influenced by self-efficacy and satisfaction and negatively influenced by procrastination and social relatedness. Thus, the results shed light on how instructors can design on-campus and distance tutorials to promote effective learning.