This study aims at highlighting the relationship between mastery learning models and academic performance in mathematics, moderated by the number of hours allotted to studying mathematics. There are 305 first to eighth-grade students who learn at "Nae A. Ghica Middle School" in Romania. Students in sixth, seventh, and eighth grades (n=101) were selected to participate in this research because they study both algebra and geometry. We have used purposive sampling to control certain variables, i.e., mastery learning strategies and academic performance. The data were analyzed in Jamovi (2022). The level of performance was measured according to the progress students made. Data analysis revealed that the moderation effect of the time each student allocated to studying mathematics individually is not statistically significant in the relationship between the mastery learning model and academic performance in mathematics. This study was conducted on a small number of students, so it is recommended to be expanded on a larger scale.