The Center for Applied Special Technology (CAST) has researched and developed Universal Design for Learning (UDL), an educational framework that recognizes learner variability and aims to provide flexible instructional techniques. UDL is based on three principles - providing multiple means of representation, action and expression, and engagement. CAST outlines nine UDL guidelines across these three principles to reduce barriers and support diverse learners, including those with disabilities, English learners, gifted students, and others. UDL uses technology and differentiated instruction to customize learning for each student. An example is the software Kid'sVid, which teaches video production skills through individualized projects and teacher evaluation rubrics.