An Inquiry-Based Lab Exercise Investigating Student Cortisol Responses to Giving a Graded In-Class Presentation.

Inquiry-based lab exercises have been shown to enhance student scientific skills and confidence, increase inclusivity for underrepresented populations, and improve persistence in science. Here I share the results and learning outcomes of an inquiry-based laboratory project investigating salivary cortisol responses to psychosocial stressors in an upper-level Comparative Neuroendocrinology course at a small liberal arts college. In this experiment, students collected saliva samples from themselves during a normal lab day (baseline) and then 10 minutes after giving a graded, in-person presentation on a scientific journal article. We used a short, student-generated survey to measure self-reported anxiety levels, feelings about public speaking, and current workload. In a subsequent lab exercise, students performed a simulated enzyme-linked immunosorbent assay (ELISA) which was designed to illustrate important concepts in ELISA design including the usage of the standard curve and the importance of proper controls. I then provided students with their own anonymized data and collaborated with them to carry out the statistical analysis of the class dataset. The students collectively found that the experience of giving a graded presentation significantly increased salivary cortisol concentrations compared to baseline and that the increase in cortisol is positively associated with students' self-reported experience of stress in response to public speaking. The multiple lab exercises culminated in a summative assignment to design a clear scientific poster sharing the results. The project led to extremely high student motivation and provided students with hands-on experience using foundational neuroendocrinological methods-as both the researcher and the subject.