Teaching materials are a key component in most language programs. Whether the teacher uses a textbook, institutionally prepared materials, or his or her own materials, instructional materials generally serve as the basis for much of the language input learners receive and the language practice that occurs in the classroom. In the case of inexperienced teachers, materials may also serve as a form of teacher training - they provide ideas on how to plan and teach lessons as well as formats that teachers can use. Much of the language teaching that occurs throughout the world today could not take place without the extensive use of commercial materials. These may take the form of (a) printed materials such as books, workbooks, worksheets, or readers; (b) nonprint materials such as cassette or audio materials, videos, or computer-based materials; (c) materials that comprise both print and nonprint sources such as self-access materials and materials on the Internet. In addition, materials not designed for instructional use such as magazines, newspapers, and TV materials may also play a role in the curriculum.

Cunningsworth (1995, 7) summarizes the role of materials (particularly course books) in language teaching as:

• a resource for presentation materials (spoken and written)

• a source of activities for learner practice and communicative interaction

• a reference source for learners on grammar, vocabulary, pronunciation, and so on

• a source of stimulation and ideas for classroom activities