This document discusses instructional materials for language courses. It defines instructional materials as printed materials like books and worksheets or non-printed materials like audio recordings and videos. Instructional materials serve four main functions: as a source of language, as learning support, for motivation and stimulation, and for reference. The document also discusses the differences between authentic materials created for real-world use and created materials designed specifically for language teaching. It claims authentic materials are generally preferred because they contain real language examples. Finally, it outlines the process of preparing instructional materials which involves creating an outline, examining existing materials, arranging or modifying those materials, preparing new materials, and selecting learning activities.