They seem to show, on the other hand, that much longer practice periods than are customary in the common schools are probably entirely allowable, and that much shorter intervals are allowable than those customary between the just learning and successive ‘reviews’ in schools."[4] This statement leaves the terms very long and very short to be defined, but at present the experimental results are too contradictory to permit of anything more specific.  However, a few suggestions do grow from these results.  The practice period should be short in proportion as these factors are present:  first, young or immature minds; second, mechanical mental processes as opposed to thought material; third, a learner who “warms up” quickly; the presence of fatigue; a function near its limit.  Thus the length of the optimum period must vary with the age of the learner, the subject matter, the stage of proficiency in the subject, and the particular learner.  The same facts must be taken into consideration in deciding on the optimum interval.  One fact seems pretty well established in connection with the interval, and that is that a comparatively short period of practice with a review after a night’s rest counts more than a much longer period added to the time spent the evening before.

There are certain suggestions which if carried out help the learner in his memorizing.  In the first place, as the number of associates is one factor determining recall, the fact to be remembered should be presented in many ways, i.e., appealing to as many senses as possible.  In carrying this out, it has been the practice of many teachers to require the material to be remembered to be acted out or written.  This is all right in so far as the muscular reactions required are mechanical and take little attention.  If, on the other hand, the child has to give much attention to how he is to dramatize it, or if writing in itself is as yet a partially learned process, the attention must be divided between the fact to be memorized and its expression, and hence the desired result is not accomplished.  Colvin claims that “writing is not an aid to learning until the sixth or seventh grade in the schools.”  This same fact that an association only partly known is a hindrance rather than a help in fixing another is often violated both in teaching spelling and language.  If the spelling of “two” is unknown or only partly known, it is a hindrance instead of a help to teach it at the same time “too” is being taught.  Second, the learner should be allowed to find his own speed, as it varies tremendously with the individual.  Third, rhythm is always an aid when it can be used, such as learning the number of days in each month in rhyme.  Fourth, after a period of hard mental work a few minutes (Pillsbury thinks three to six) should elapse before definitely taking up a new line of work.  This allows for the so-called “setting” of associations, due to the action of the general law of inertia, and tends to diminish the possibility