Plans I and II are obviously inferior to Plans III and IV; and Plan IV gives promise of being more effective than Plan III, since there seems danger that the pupil working by Plan III might in the ten weeks lose too much of what he had gained in the initial practice, and so again in the next ten weeks.
Fig. 7.—Plan I. 200 practices distributed somewhat evenly over 3½ years of 10 months. In Figs. 7, 8, 9, and 10, each tenth of an inch along the base line represents one month. Each hundredth of a square inch represents four practices, a little square 1⁄20 of an inch wide and 1⁄20 inch high representing one practice.
Fig. 8.—Plan II. 200 practices distributed haphazard over 3½ years of 10 months.
Fig. 9.—Plan III. A learning period, three reviews, and incidental practice.
It is not wise, however, to try now to make close decisions in the case of practice with division by a fraction; or to determine what the best distribution of practice is for that or any other ability to be improved. The facts of psychology are as yet not adequate for very close decisions, nor are the types of distribution of practice that are best adapted to different abilities even approximately worked out.
