Undergraduate science education often focuses on how experiments are carried out and the scientific knowledge as communicated in the research literature, but neglects engaging students in the critical peer review process that validates such scientific findings. We propose integrating peer review teaching into undergraduate STEM curricula to unveil this critical, yet hidden, aspect of scientific practice. We developed and evaluated a constructivist, service-learning curriculum where undergraduate biology students learn about peer review, then write and publish reviews of preprints. Initially piloted with advanced students at Mt. Holyoke, this project adapted the course for first-semester students at Oxford College of Emory University. We investigated how authentic peer review engagement impacts students' scientific literacy, identity, and understanding of the course topic: the Covid-19 pandemic. The 15-week course, delivered to 17 first-year students, covered peer review history, sociology, and mechanics, followed by practical evaluation and construction of review reports. Students completed individual and group peer reviews of SARS-CoV-2 preprints. Surveys assessing science literacy, identity, belonging, and SARS-CoV-2 biology understanding were conducted throughout the course and analyzed using one-way ANOVA and paired t-tests. Results showed increases in students' self-efficacy, science identity, and networking factors after the first peer review assignment, with more significant increases following group reviews. These trends mirrored those observed in the previous iteration with advanced students at Mt. Holyoke. Significant gains across all metrics were reported upon course completion. Our study concludes that: 1. Exposing students to hidden aspects of science, like peer review, can enhance their affinity with the scientific community and understanding of scientific processes. 2. Students with limited experience can learn to provide effective peer reviews, suggesting implications for broadening the pool of potential peer reviewers and their training in scientific publishing.
