Courses taken beyond the first year by students engaged in STEM majors sometimes show different behaviors. This is likely due to selection among the students who enroll. One example is provided by the mathematics sequence of courses MATH 115/116/215/216. Female students differentially depart from from this sequence throughout: they make up 44% of MATH 115 students and only 26% of MATH 216 students. The gradual shift in gendered performance difference in these courses may be due to these differential selection effects.