The document discusses the role and design of instructional materials. It begins by outlining different forms of teaching materials, including printed materials like books and worksheets, and non-printed materials like audio recordings and videos. It then discusses the functions of materials, including as a source of language, learning support, motivation, and reference. The document also discusses the advantages and criticisms of using authentic versus created instructional materials. Overall, the document provides guidance on evaluating, selecting, adapting, developing, and monitoring the use of effective instructional materials.