Exercise guides at the beginning of each set of exercises suggest particular problems to which students can turn in order to practice certain skills or to improve their understanding of particular ideas. To use these simple tables effectively, students must understand the vocabulary of the subject, and they must connect the vocabulary to what they know.
Consequently, the ostensible purpose of these guides--mapping course concepts into exercises--is realized only for those students who understand the elements in the domain of this mapping. To use a different metaphor, students must distinguish among the trees in the forest before an exercise guide becomes a useful map through it. Hence, the subversive purpose of the exercise guides is fostering understanding through mastery of vocabulary. Students who know enough to solve the inverse problem--using an exercise guide to determine which ideas apply to a given problem--already understand enough to make the exercise guide irrelevant.