We must take into account at the very beginning the fundamental truth stated by Thorndike,[54] that “achievement is a measure of ability only if the conditions are equal.”  Corollary to that is the fact that the same uniform conditions and requirements are often very unequal as applied to different individuals.  The equalization of educational opportunity does not at all mean the same duplicated method or content for all.  That interpretation will controvert the very spirit and purpose of the principle stated.  Any inflexible scheme which attempts to fashion all children into types, according to preconceived notions, and whose perpetuity is rooted in a psychology based on the uniformity of the human mind, simply must give way to the newer conception which harmonizes with the psychic laws of the individual, or else continue to waste much time and energy in trying to force pupils to accomplish those things for which they have neither the capacity nor the inclination.  It is accordingly obligatory on the school to give intelligent and responsive recognition to the wide differentiation of social demands, and to the extent and the continuity of the individual differences of pupils.

1.  ORGANIZATION AND ADAPTATION IN RECOGNITION OF THE INDIVIDUAL DIFFERENCES IN ABILITIES AND INTERESTS

If the school failures are to be substantially reduced, the teaching of the school subjects with the chief emphasis on the pupil must surely replace the practice of teaching the subjects primarily for their own sake.  This ‘subject first’ treatment must give place to the ’pupil first’ idea.  No subject then will overshadow the pupil’s welfare, and the pupil will not be subjected to the subject.  Education in terms of subject-matter is well designed to produce a large crop of failures.  Neither the addition or subtraction of subjects is urged primarily, but the adaptation and utilization of the school agencies so as to make the pupils as efficient and as productive as possible, by recognizing first of all their essential lack of uniformity in reference to capacities and interests,—­not only as between different individuals, but in the same individual at different ages, at different stages of maturity, and in different kinds of subjects.  This conception precludes the school employment of subjects and methods for all alike which are obviously better adapted to the younger than to the older.  Neither does it overlook the fact that the attitude of more mature pupils toward authority and discipline is essentialy different from that of the younger boys and girls; that a subject congenial to some pupils will be intolerable and nearly if not quite impossible for others; or that an appeal designed mainly to reach the girls will not reach boys equally well.  In brief, the treatment proposed here is neither radical nor novel, but it is simply the institution of applied psychology as pertaining to school procedure.  What the more modern experimental psychology has established must be utilized in the school, at the expense of the more obsolete and traditional.  Psychology now generally recognizes the existence of what the general school procedure implies does not exist, namely, the wide range of individual differences.