In this article Robert asks the textbook companies about how they address relevance. The point he makes below is also one of my favorites in this series, which, to repeat, if read with an open mind by anyone in the field of language instruction, spells the certain demise of the big textbook companies:
How does the textbook address relevance? (How does it connect to the real life of students? How do the textbook authors know what prior knowledge any given group of students may have? How are drills and worksheets engaging?) How is the textbook’s material personalized? How is the textbook’s material student-centered? By presenting a scope and sequence that is predetermined, the textbook asks students to learn according to a grammar-centered syllabus rather than exploring what interests them. Teaching with Comprehensible Input allows the teacher to explore student interests and is the ultimate in student-centered instruction when properly done.