Abstract: This paper describes the design and evaluation of G2GWiki, a wiki created for cross-classroom collaborative project-based learning (C3PjBL). C3PjBL is an emerging learning strategy that allows student-groups from different classrooms to work collaboratively to complete curriculum-based projects using wikis. The created wikis are crowdsourced which allows them to be queried using search terms. G2GWiki was evaluated by Primary School teachers who participated in a C3PjBL workshop. These participants were asked to engage in a C3PjBL activity and complete a post-workshop questionnaire. The questionnaire queried participants’ perceptions of the function, design, and ease of use of G2GWiki and its syntax. Participants described G2GWiki as an effective tool which allows groups to work on projects across classrooms, while developing critical thinking skills. Participants also found G2GWiki easy and fun to use. G2GWiki’s search engine was also evaluated using a test-set of 55 wikis. The results show that the correct wiki was returned in the top three search results ninety-five percent of the time. G2GWiki’s design and feature-set provides an effective mechanism for C3PjBL.