ore added gain.
All experimental evidence is against the opinion that mere disuse in and
of itself produces gain. In fact, all results point to the fact that
disuse brings deterioration.

In the case of memory, as has already been described in habit formation,
reviews which are organized with the period between repetitions only
gradually lengthened may do much to insure permanence. It is entirely
feasible to have children at the end of any school year able to repeat
the poems or prose selections which they have memorized, provided that
they have been recalled with sufficient frequency during the course of
the year. In a subject like geography or history, or in the study of
mathematics or science, in which logical memory is demanded, systematic
reviews, rather than cramming for examinations, will result in
permanence of command of the facts or principles involved, especially
when these reviews have involved the right type of organization and as
many associations as is possible.

It is important in those subjects which involve a logical organization
of ideas to have ideas associated around some particular problem or
situation in which the individual is vitally interested. Children may
readily forget a large number of facts which they have learned about
cats in the first grade, while the same children might remember, very
many of them, had these facts been organized round the problem of taking
care of cats, and of how cats take care of themselves. A group of
children in an upper grade may forget with great rapidity the facts of
climate, soil, surface drainage, industries, and the like, while they
may remember with little difficulty facts which belong under each of
these categories on account of the interest which they have taken in the
problem, "Why is the western part of the United States much more
sparsely populated than the Mississippi Valley?" Boys and girls who
study physics in the high school may find it difficult to remember the
principles involved in their study of heat if they are given only in
their logical order and are applied only in laboratory exercises which
have little or no meaning for them, while the same group of high school
pupils may remember without difficulty these same laws or principles if
associated round the issue of the most economical way of heating their
houses, or of the best way to build an icehouse.

There has been in our school system during the past few years more or
less of a reaction