Rising tuition rates across colleges and universities contribute to the mounting financial strain on students. In response to rising costs, literature details that students seek to bolster their financial security by working additional hours per week, consequently leading to less available time. Previous studies have focused on the negative associations with GPA but not with in-class points. We observed this relationship within a 77-student 200-level genetics course and associated lab. Students working 20+ hours per week (59.7% of students) fared significantly worse on exams. These students scored significantly fewer total class points (p = 0.0089), exam points (p = 0.0255, p = 0.0028, p = 0.0311), and were more likely to incur a failed assignment sooner during the class than their counterparts (p = 0.0025). We observed these trends again in a 34-student 400-level immunology validation cohort (p = 0.0032). These findings represent the first quantitative analysis of employment vs. numerical biology exam and course scores. They are an important step toward identifying and treating the underlying factors associated with reduced STEM performance, retention, and well-being, and represent a forewarning of an approaching higher education crisis as institutions seek to retain and support underrepresented students.