With respect to students as economizing, that is maximizing, agents when buying text books. All maximization takes place in knowledge constraints. The student, by definition, does not know what is in the book, or whether [their] interest and motivation will persist though the course. The fact that they buy the book is not an indication of established preferences, or whether they will read it; and even if they do read it, whether they will comprehend the contents. Indeed, some will read and comprehend, and get a good mark, and regret for the rest of their lives that they bought the book and took the course. Robin Neill