Instructional Materials are the materials, like textbooks, lesson & unit plans, and assessments, that teachers use to teach and assess student learning. Not all instructional materials are created equal. Research shows that one of the best ways to quickly improve student learning and achievement is to ensure teachers are using high-quality instructional materials in their classrooms. Materials matter and utilizing high-quality instructional materials in a classroom can make a 40 times larger impact in student achievement than reducing class size.