The document discusses several principles of materials design according to different authors such as Nunan, Tomlinson, Hutchinson and Waters. Key principles discussed include ensuring materials are clearly linked to curriculum goals and objectives, include authentic texts and tasks, stimulate interaction, allow focus on language forms, and encourage applying skills outside the classroom. Frameworks for materials design incorporate elements like input, content focus, language focus, and communicative tasks. There is no single agreed set of principles but areas of agreement include making materials relevant and requiring learner self-investment.