This document summarizes a study on the reliability of peer assessment in a social media course where students rated assignments using a social media app. Sixty students in the course completed individual assignments and then rated 20 assignments from peers. Their ratings were also compared to ratings from instructors and 11-year old students. The results found moderate agreement between peers and instructors, moderate agreement between peers and students, and high agreement between instructors and students, indicating that peer assessment can be a reliable approach. The researchers are working to fully integrate this peer assessment method into the Graasp collaboration platform.