First and
most obvious, we've organized the entire, massive K — 12 system around an age - based, grade - level, 180 - days - per -
year calendar; around mostly self - contained and generally low - tech classrooms; and around a pedagogical model centered on a
single teacher teaching a uniform curriculum to twenty to thirty children for a prescribed amount of time each day, children who don't have much
in common except that they're more or less the same age and (usually) live
in pretty much the same community.