cially in our large graded schools. But we can at any rate adjust our requirements with some degree of accuracy to the average capacity of the whole.
Regarding the number of hours of mental application per day which may be safely expected of a pupil in school, investigations have tended to show that there is a danger of requiring too many. When pupils return to school morning after morning without having recovered from the previous day's labors, it is evident that too heavy draughts are being made upon their nervous capital. It may be said in reply that many factors conspire to produce this depleted condition, as insufficient sleep, inadequate nutrition, and outside duties; but the answer is that under such unfavorable circumstances less work may be demanded. As the curriculum is planned in many places, alike in graded and ungraded schools, the pupil is expected to be employed in the school for five or six hours a day no matter what may be his age, and to this work should be added studies at home for the older students. Now, as Kraeplin[1] has justly observed. Nature ordains that a young child should not give six hours' daily concentrated attention in the schoolroom, but, rather, she has taken pains to implant deeply within him a profound instinct to preserve his mental health by refusing to attend to hard work for such a long period. Consequently, in such an educational regime, the mind of the pupil continually wanders from the duties in hand. The most serious aspect of this is apparent, that when attention is constantly demanded and not given, or when a pupil is pretending or attempting to keep his thoughts turned in a given direction, yet allows them to drift aimlessly because he is practically unable to control them, he is acquiring an unfortunate habit of mental dissipation. It seems certain that healthful and efficient mental activity requires that a child apply himself in a maximum degree for a relatively short period, the duration differing with the age of the individual and the balance of nervous energy to his credit; and then he should relax, attention being released for a time.
Experiments conducted by Burgerstein[2] and at Leland Stanford Junior University[3] emphasize a particular phase of this principle—that too long continued mental application without relaxation induces fatigue more readily than when there are comparatively short periods of effort, followed by intermissions of rest. Thus when pupils (and the younger they are the more is this true) have a given amount of work to do requiring their attention say for an hour and a half they will accomplish most with least waste of energy by breaking up this long stretch into several parts, interspersing a few min-
