Free materials serve a meaningful purpose in education by providing tools to support teaching and learning, but free resources are not necessarily open resources. “Free” means that there is no required cost to access materials. It does not mean that users may also reuse, modify, or share the materials. When a resource is open, users know they can reuse and share the resource widely, so long as they abide by the terms of its creator. Open materials also allow users to revise and remix them with other open resources or self-generated content to produce new material. These terms and permissions are typically established in the open license applied to the work.