TMOSS: Using Intermediate Assignment Work to Understand Excessive Collaboration in Large Classes.

As computer science classes grow, instructor workload also increases: teachers must simultaneously teach material, provide assignment feedback, and monitor student progress. At scale, it is hard to know which students need extra help, and as a result some students can resort to excessive collaboration--using online resources or peer code--to complete their work. In this paper, we present TMOSS, a tool that analyzes the intermediate steps a student takes to complete a programming assignment. We find that for three separate course offerings, TMOSS is almost twice as effective as traditional software similarity detectors in identifying the number of students who exhibit excessive collaboration. We also find that such students spend significantly less time on their assignment, use fewer class tutoring resources, and perform worse on exams than their peers. Finally, we provide a theory of the parametric distribution of typical student assignment similarity, which allows for probabilistic interpretation.