Looking around in the US[1], it looks like legally the cap can be from 1:15 - 1:25 (K-3). It looks like 1/3 of states don't have any legal cap. Funny enough, th

Looking around in the US[1], it looks like legally the cap can be from 1:15 - 1:25 (K-3). It looks like 1/3 of states don't have any legal cap. Funny enough, this chart[2] correlating reading performance and class size stops at 1:21 for 4th and 8th grade. [1] http://ecs.force.com/mbdata/MBQuest2RTanw?rep=KK3Q1807 http://ecs.force.com/mbdata/MBQuest2RTanw?rep=KK3Q1807 [2] https://en.wikipedia.org/wiki/Student%E2%80%93teacher_ratio#/media/File:US_correlation_between_class_size_and_reading_performance.png https://en.wikipedia.org/wiki/Student%E2%80%93teacher_ratio#...