It is unnecessary to discuss at length presentation as a factor in the recitation, because our last chapter covered the topic under the captions of observation and communication. The function of presentation is to supply materials that force home the nature of a problem and furnish suggestions for dealing with it. The practical problem of the teacher is to preserve a balance between so little showing and telling as to fail to stimulate reflection and so much as to choke thought. Provided the student is genuinely engaged upon a topic, and provided the teacher is willing to give the student a good deal of leeway as to what he assimilates and retains (not requiring rigidly that everything be grasped or reproduced), there is comparatively little danger that one who is himself enthusiastic will communicate too much concerning a topic. [Sidenote: The pupil's responsibility for making out a reasonable case] II. The distinctively rational phase of reflective inquiry consists, as we have already seen, in the elaboration of an idea, or working hypothesis, through conjoint comparison and contrast, terminating in definition or formulation. (_i_) So far as the recitation is concerned, the primary requirement is that the student be held responsible for working out mentally every suggested principle so as to show what he means by it, how it bears upon the facts at hand, and how the facts bear upon it. Unless the pupil is made responsible for developing on his own account the _reasonableness_ of the guess he puts forth, the recitation counts for practically nothing in the training of reasoning power. A clever teacher easily acquires great skill in dropping out the inept and senseless contributions of pupils, and in selecting and emphasizing those in line with the result he wishes to reach. But this method (sometimes called "suggestive questioning") relieves the pupils of intellectual responsibility, save for acrobatic agility in following the teacher's lead. [Sidenote: The necessity for mental leisure]