The document discusses the history and evolution of literature on materials development for language learning. It covers several key topics:
1) The types and purposes of instructional materials.
2) The growth of publications on materials development, evaluation, and adaptation from the 1970s to present.
3) Frameworks and guidelines for evaluating materials, moving from checklists to more principled approaches considering context and beliefs.
4) Reports on evaluating currently used materials and adapting materials to make them more suitable for different contexts and learners.
5) Calls for more research on the actual effects of materials on learners and the processes involved in writing materials.