The purpose of this single-case descriptive study was to explore student and instructor perceptions of Supplemental Instruction (SI) in an upper-level chemistry course (Physical Chemistry). The course has a reputation for being particularly challenging, an academic hurdle or barrier for students in the science, mathematics and engineering (SME) disciplines. This study provided an opportunity to better understand why students in an advanced "barrier" course participate in SI, and why SI is perceived as an effective resource in upper-level courses. Determining the perceived benefit of SI as a way to overcome these barriers may positively contribute to persistence.

In designing this study, the researcher sought to answer two primary questions: (1) Why do students in Physical Chemistry participate in SI; and (2) is SI an effective strategy supporting persistence in SME majors? These questions were explored through a case study methodology that included a focus group, one-on-one interviews with instructors and six enrolled students, document review and class and SI statistics. Findings indicated four major factors that related to students' participation in these SI sessions: (1) anxiety about the course initiated by the reputation of this difficult required course; (2) the course content, complicated by the use of mathematics and composition of the subject matter; (3) characteristics of enrolled students; and (4) nature and benefit of academic resources. The combination of course anxiety and a required course with difficult content generates the cycle of an academic barrier.

Results also suggested several interrelated conclusions about the value of SI as an academic resource. SI seemed to reduce anxiety, and supported students' learning. A comparison of course grades before and since the inclusion of SI in Physical Chemistry demonstrated a statistically significant increase in higher grades. This combination of academic success and positive social experiences suggests that SI is a valuable resource for overcoming academic barriers and positively contributing to student persistence.