It must be borne in mind that in a conceptual or an inductive lesson care is to be taken by the teacher to see that the particulars are sufficient in number and representative in character. As already pointed out, crude notions often arise through generalizing from too few particulars or from particulars that are not typical of the whole class. Induction can be most frequently employed in elementary school work in the subjects of grammar, arithmetic, and nature study. INDUCTIVE-DEDUCTIVE LESSONS Before we leave this division of general method, it should be noted that many lessons combine in a somewhat formal way two or more of the foregoing lesson types. In many inductive lessons the step of application really involves a process of deduction. For example, after teaching the definition of a noun by a process of induction as outlined above, we may, in the same lesson, seek to have the pupil use his new knowledge in pointing out particular nouns in a set of given sentences. Here, however, the pupil is evidently called upon to discover the value of particular words by the use of the newly learned general principle. When, therefore, he discovers the grammatical value of the particular word "Provender" in the sentence "Provender is dear," the pupil's process of learning can be represented in the deductive form as follows: All naming words are nouns. _Provender_ is a naming word. _Provender_ is a noun. Although in these exercises the real aim is not to have the pupil learn the value of the individual word, but to test his mastery of the general principle, such application undoubtedly corresponds with the deductive learning process previously outlined. Any inductive lesson, therefore, which includes the above type of application may rightly be described as an inductive-deductive lesson. A great many lessons in grammar and arithmetic are of this type. CHAPTER XVI THE LESSON UNIT