(_iii_) The material furnished by way of information should be relevant to a question that is vital in the student's own experience. What has been said about the evil of observations that begin and end in themselves may be transferred without change to communicated learning. Instruction in subject-matter that does not fit into any problem already stirring in the student's own experience, or that is not presented in such a way as to arouse a problem, is worse than useless for intellectual purposes. In that it fails to enter into any process of reflection, it is useless; in that it remains in the mind as so much lumber and débris, it is a barrier, an obstruction in the way of effective thinking when a problem arises. [Sidenote: and to prior systems of experience] Another way of stating the same principle is that material furnished by communication must be such as to enter into some existing system or organization of experience. All students of psychology are familiar with the principle of apperception--that we assimilate new material with what we have digested and retained from prior experiences. Now the "apperceptive basis" of material furnished by teacher and text-book should be found, as far as possible, in what the learner has derived from more direct forms of his own experience. There is a tendency to connect material of the schoolroom simply with the material of prior school lessons, instead of linking it to what the pupil has acquired in his out-of-school experience. The teacher says, "Do you not remember what we learned from the book last week?"--instead of saying, "Do you not recall such and such a thing that you have seen or heard?" As a result, there are built up detached and independent systems of school knowledge that inertly overlay the ordinary systems of experience instead of reacting to enlarge and refine them. Pupils are taught to live in two separate worlds, one the world of out-of-school experience, the other the world of books and lessons. CHAPTER FIFTEEN THE RECITATION AND THE TRAINING OF THOUGHT [Sidenote: Importance of the recitation] In the recitation the teacher comes into his closest contact with the pupil. In the recitation focus the possibilities of guiding children's activities, influencing their language habits, and directing their observations. In discussing the significance of the recitation as an instrumentality of education, we are accordingly bringing to a head the points considered in the last three chapters, rather than introducing a new topic. The method in which the recitation is carried on is a crucial test of a teacher's skill in diagnosing the intellectual state of his pupils and in supplying the conditions that will arouse serviceable mental responses: in short, of his art as a teacher. [Sidenote: Re-citing _versus_ reflecting]