t certain ideas be associated so that one calls up the
other. Teachers and parents, knowing these desirable connections,
endeavor to fix them in the minds of children by repetition. The
important facts of history, literature, civics, and science we endeavor,
by means of repetition, to fasten in the child's mind.

=Vividness and Intensity of Experience.= A vivid experience is one that
excites and arouses us, strongly stimulating our feelings. Such
experiences establish strong bonds of connection. When I think of a
railroad wreck, I think of one in which I participated. The experience
was vivid, intense, and aroused my emotions. I hardly knew whether I was
dead or alive. Then, secondly, I usually think of a wreck which I
witnessed in childhood. A train plunged through a bridge and eighteen
cars were piled up in the ravine. The experience was vivid and produced
a deep and lasting impression on me.

The practical significance of this factor is, of course, great. When
ideas are presented to pupils these ideas should be made clear. Every
conceivable device should be used to clarify and explain,--concrete
demonstration, the use of objects and diagrams, pictures and drawings,
and abundant oral illustration. We must be sure that the one taught
understands, that the ideas become focal in consciousness and take hold
of the individual. This is the main factor in what is known as
"interest." An interesting thing is one that takes hold of us and
possesses us so that we cannot get away from it. Such experiences are
vivid and have rich emotional connections or accompaniments. Ideas that
are experienced together at such times are strongly connected.

=Mental Set or Attitude.= Another influence always operative in
determining the association of ideas is mental set. By mental set we
mean the mood or attitude one is in,--whether one is sad or glad, well
or ill, fresh or fatigued, etc. What one has just been thinking about,
what one has just been doing, are always factors that determine the
direction of association. One often notices the effects of mental set in
reading newspapers. If one's mind has been deeply occupied with some
subject and one then starts to read a newspaper, one may actually
miscall many of the words in the article he is reading; the words are
made to fit in with what is in his mind. For example, if one is all
wrought up over a wedding, many words beginning with "w" and having
about the same length as the word "wedding