In today’s Wall Street Journal, University of Arkansas professor Jay Greene sets the record straight on claims that the United States needs more teachers.

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.

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). Unless the next teacher-hiring binge produces something that the last several couldn’t, there is no reason to expect it to contribute to student outcomes.

Greene points out that technology is one way to increase educational productivity.  He writes,

Then there is the trade-off between labor and capital. Instead of hiring an army of additional teachers, we could have developed and purchased innovative educational technology. The path to productivity increases in every industry comes through the substitution of capital for labor. We use better and cheaper technology so that we don’t need as many expensive people. But education has gone in the opposite direction, making little use of technology and hiring many more expensive people.

Unfortunately, lawmakers will continue to encounter significant pressure to increase the size of the education labor force.  Many will be temped to do so, despite evidence that it is a poor return on investment.