From the website: "CK-12 will provide open-source content and technology tools to help teachers provide learning for students in a global world. Free access to high-quality, customizable educational content in multiple modalities suited to multiple student learning styles, levels, resources
and use content acceptance will allow teachers, students and others to
innovate and experiment with new models and modalities of learning. CK-12 helps students and teachers alike by enabling rapid customization and experimentation of teaching and learning styles. "