… Since 1970, the public school workforce has roughly doubled—to 6.4 million from 3.3 million—and two-thirds of those new hires are teachers or teachers’ aides. Over the same period, enrollment rose by a tepid 8.5%. Employment has thus grown 11 times faster than enrollment. If we returned to the student-to-staff ratio of 1970, American taxpayers would save about $210 billion annually in personnel costs. …  WSJ.