no attempt is made to develop an utterly new class
notion, or concept; the pupils in fact may already know the class of
objects in a general way and be acquainted with many of their
characteristics. The object of the lesson is, therefore, to render the
concept more scientific by having it include the qualities which
essentially mark it as a class and especially separate it from other
co-ordinate classes. In studying the grasshopper; for instance, in
entomology, the purpose is not to give the child a notion of the insect
in the ordinary sense of the term. This the pupil may already have. The
purpose is rather to enable him to decide just what general
characteristics distinguish this from other insects. The lesson may,
therefore, leave out of consideration features which are common to all
grasshoppers, simply because they do not enter into a scientific
differentiation of the class.

2. TO ENLARGE A CONCEPT

In many lessons the aim seems to be chiefly to enlarge certain concepts
by adding to their intensiveness. The pupil, for instance, has a
scientific concept of a triangle, that is, one which enables him to
distinguish a triangle from any other geometrical figure. He may,
however, be led to see further that the three angles of every triangle
equal two right angles. This is really having him discover a further
attribute in relation to triangles, although this knowledge is not
essential to the concept as a symbol of the members of the class. In the
same way, in grammar the pupil is taught certain attributes common to
verbs, as mood and tense, although these are not essential attributes
from the standpoint of distinguishing the verb as a special class of
words.

3. TO BUILD UP NEW CONCEPTS

=A. Presentation of Unknown Individuals.=--In many lessons the chief
object seems to be, however, to build up a new concept in the mind of
the child. This would be the case when the pupil is presented with a
totally unknown object, say a platypus, and called upon to examine its
characteristics. In such lessons two important facts should be noticed.
First, the child finds seemingly little difficulty in accepting a single
individual as a type of a class, and is able to carry away from the
lesson a fairly scientific class notion through a study of the one
individual. In this regard the pupil but illustrates what has been said
of the ability of the child to use his early percepts as standards to
interpret other individuals. The pup