Using Peer Code Review as an Educational Tool

Code-review, the systematic examination of source code, is widely used in industry, but seldom used in courses. We designed and implemented a rubric-driven online peer code-review system (PCR) that we have deployed for two semesters, during which 228 students performed over 1003 code reviews. PCR is designed to meet four goals: (1) Provide timely feedback to students on their submissions, (2) Teach students the art of code review, (3) Allow custom feedback on submissions even in massive online classes, and (4) Allow students to learn from each other. We report on using PCR, in particular, the accuracy of student-based reviews, the surprising number of free-form comments made by students, the variability of staff-based reviews, how student engagement impacts the accuracy, the additional workload, and anecdotal perspectives of students. We describe some critical design considerations for PCR including rubric design, the importance of PCR training on each assignment to acclimate students to the rubric, and how we match student reviewers to student submissions.