cK-12 is a powerful curriculum platform that has been used in MPS in various curricular areas. CK-12 Foundation is a non-profit organization dedicated to increasing access to high quality educational materials for K-12 students all over the world. We offer free high-quality, standards-aligned, open content in the STEM subjects. By providing these free resources, CK-12 is working toward educational equity for all. Source: cK-12