This commentary describes the limitations of 40-minute class period times. The forty-minute system makes hash of the lives of teachers, especially in small schools, and about 80 percent of high schools have fewer than two hundred pupils. These small schools crowd their forty-minute periods with as many diverse and unrelated activities as possible, forcing teachers to prepare multiple subjects, some of which they may not yet have mastered. A serious outcome of this arrangement is that students are pulled between diverse and conflicting stimuli. This issue is projected to get worse before it gets better, as major subject teachers have powerful organization decision-makers that can pull strings to keep their subjects in the schedule program. [This article was originally published in "School Review" v53, no. 3, p162-169 (March 1945) It is reprinted here with the kind permission of the University of Chicago Press.]