Abstract: Cross-Classroom Collaborative Project-Based Learning (C3PjBL) is the collaboration of student-groups on projects across classrooms. In this environment, students develop their higher-order thinking skills while solving real-life problems; and teachers increase their knowledge during teacher-teacher collaborations. Given that C3PjBL is an evolving learning strategy, modern online tools do not permit the creation of this environment. This paper discusses the theoretical foundation of C3PjBL; describes a Web-based C3PjBL Management System (called G2GCollaborate); and presents a case study of primary school teachers who participated in a simulated C3PjBL activity. Participants noted that the system can be used to build projects for children of all ages and groups can collaborate without having to physically move from their classrooms. Participants highlighted implementation time as a concern, however, G2GCollaborate’s automatic group formation and data entry clerk functionality removes this adoption barrier. This system allows students to teach and learn from one another; similarly, teachers act as both resource persons and learners while engaging in professional development.