Wikipedias are online spaces for collaboration and the development and sharing of knowledge. The main English language Wikipedia presents several difficulties for language learners and instructors. Excessive jargon, specialisation, and uncontrolled language and style make many articles inaccessible for readers. Gatekeeping and a sometimes hostile culture can make contributing difficult to impossible. Simple English Wikipedia (SEWP) greatly reduces these barriers and aims to serve younger readers and English language learners by using controlled vocabulary and grammar. The wiki also provides spaces and tools for schools. This poster will dispel some of the criticisms of SEWP and demonstrate the affordances of this platform for student-student, student-instructor, and student-public cooperation in developing and using content-based or CLIL appropriate materials for the classroom and for independent learning.