The CK-12 Foundation is a non-profit organization that works to increase access to high-quality educational materials for K-12 students globally. The organization offers standards-based materials including flexbooks (digital textbooks) and an interactive curriculum for STEM subjects. Students can practice key skills with adaptive practice, simulations, games, discussions, and more. All of the materials offered can be customized to meet the individual learning needs of students. Check out all that CK-12 has to offer here.