CAST is a nonprofit research and development organization that works to expand learning opportunities for all individuals, especially those with disabilities, through Universal Design for Learning (UDL). Developed by CAST, UDL is a widely recognized framework to guide the design of learning experiences to proactively meet the needs of all learners. The organization conducts research and provides training and resources for k-12, higher education, and workplaces. The website has useful tools for educators, organizations, and businesses.
Teachers and others will be particularly interested in the free resources section, which includes tools such as UDL guidelines for curriculum design and a UDL book builder. The Design Learning portal hosts an online learning community and tons of pd resources to help teachers bring UDL to the classroom.