It is certainly much better to have the textbook before one than to teach the lesson after a disconnected and haphazard fashion from lack of familiarity with its points. An excellent substitute for the text, however, is an outline, or plan of the lesson embodying the main points, illustrations, and applications to be made. Such an outline will save the teacher from wandering too far afield in the discussions, will insure unity in the lesson, and make certain that important points shall not be overlooked.
A desirable rule for the teacher to set for himself would be so to prepare for the recitation by mastery of the subject, and by lesson plan or outline, that he does not need to have the textbook open before him when the pupils do not also have their books open. The teacher who will heroically meet this standard will soon find growing in himself a feeling of mastery of his subjects and of joy in his teaching.
4. The principle of unity or continuity in questions
Questions should be so planned that they develop or bring out the unity of the lesson. It is possible for questions to be so haphazard and disconnected that the pupil receives the impression of a series of unrelated facts, rather than a unified and related subject. In good questioning, one question naturally grows out of another, so that the series develops step by step the truth contained in the lesson, and brings it to the mind of the child as a complete whole.
This means that the teacher must know the whole subject so thoroughly that the right questions come to him easily and naturally, and in the right order to bring out the successive steps of the lesson in their logical relations.
The difference between a related series of questions and an unrelated is shown in two lists which follow. Both deal with the same subject-matter, a physiology lesson on respiration. The questions of the first list are not themselves faulty, but there is no continuity among them; one does not grow out of another so as to "develop" the subject in the minds of the class.
What change takes place in the air while in the lungs?
What change takes place in the blood while in the lungs?
How many cubic inches of air will the lungs contain?
How much of this cannot be expelled by breathing out?