The Wall Street Journal reports:
For decades we have tried to boost academic outcomes by hiring more teachers, and we have essentially nothing to show for it. In 1970, public schools employed 2.06 million teachers, or one for every 22.3 students, according to the U.S. Department of Education's Digest of Education Statistics. In 2012, we have 3.27 million teachers, one for every 15.2 students.
There's more:
Yet math and reading scores for 17-year-olds have remained virtually unchanged since 1970, according to the U.S. Department of Education's National Assessment of Educational Progress. The federal estimate of high-school graduation rates also shows no progress (with about 75% of students completing high school then and now).
The law of diminishing returns applies to education.
