Serlo is Germany’s leading online learning community and software platform for Open Educational Resources (OER), it generates and maintains content for K-12 school education. With over than 8 million unique visitors in 2016, Serlo delivers 9,000 articles, videos, lectures, exercises and solutions in mathematics and other subjects. Serlo’s educational Wikipedia system provides not only access to community authored content, but also encourages new content creation and material curation. The community and the users’ feedback assures quality. Serlo Education is organized as a non-profit association with a distinctive focus on content compilation, quality management and software development.