Abstract
Prior research has shown that supplemental peer support programs in chemistry enhance student success in the parent course. But the literature lacks studies on whether participation in multiple peer-led supplemental instruction courses is more effective than just one. Here we find a statistically significant dosing effect for Peer Assisted Learning (PAL) support in organic chemistry: students who took two sequential organic chemistry PAL courses outperformed those who only took one. PAL is a peer-led supplemental instruction model where program enrollment is voluntary, but attendance is mandatory for enrolled students. Due to the optional nature of the program, we use propensity score weighting to mitigate academic and demographic variations between the two groups of students studied. Our dataset consisted of 77 Organic Chemistry II students who enrolled in the PAL support course between Fall 2020 and Fall 2024. Within this group, we compared those who also enrolled in the PAL support course for the prerequisite Organic Chemistry I class with those who did not. We found that students who took both PAL courses outperformed those who only took the second by 0.58 grade points (P = 0.028, 95% CI 0.07-1.10) in their Organic Chemistry II course grade.