This study examined the changes in mathematics achievement in certain content areas of freshmen before and after Covid-19. For this purpose, in 2019 and 2021, the diagnosis assessment and the mid-term and final exam scores for the first semester of the local engineering college students were converted into 100 points and compared in various aspects. As a result, first, the scores seem to confirm a decline in mathematics achievement in 2021 when compared to the scores achieved before the Covid-19 pandemic. Second, in the case of the upper group, online classes were more effective concerning the study of transcendental function, function and limit, derivatives, and the application of derivatives. Third, in the lower level group, the face-to-face classes were more effective regarding the study of function, transcendental function, function and limit, and integrals. Fourth, the results of the comparison of contents between the upper and lower level groups in 2019 showed that the lower level group’s achievement was higher than the upper level group’s in all areas, but that there was no statistically significant difference. Finally, the results of the comparison between the upper and lower level groups in 2021 showed that the upper level group’s achievement was higher than the lower level group’s in all areas, but that there was a statistically significant difference only when it came to the learning of integrals., in addition to the content characteristics of courses in the liberal arts area regarding the basic nature of a major.