The CK-12 Foundation is a California-based non-profit organization whose stated mission is to reduce the cost of, and increase access to, K-12 education in the United States and worldwide. CK-12 provides free and fully customizable K-12 open educational resources aligned to state curriculum standards and tailored to meet student and teacher needs. The foundation’s tools are used by 38,000 schools in the US, and additional international schools.
License: Except where otherwise noted, content is licensed under a Creative Commons (BY-NC-SA) 3.0 license.
Website: CK-12.org
Christer Gundersen 