My son asked me this the other night during the Presidential debate. He was watching on his Xbox where they had an interactive opinion poll going on while the debate was going on. Now appears this article by Jay Greene in the Wall Street Journal, addressing this very issue.

I’ve always been troubled by the lack of measurable improvement in test scores or any other measurement of student achievement as we have increased education spending and decreased class size. I’m drawn toward a model where teachers and schools really have to compete and so they either improve or fail. I agree with the experts who say we don’t need more teachers; rather we need more great teachers. But I also worry along with some of my colleagues about what happens to the special needs kids if we have a more competitive, voucher-based system.

Anyway, I thought this was a good article on the topic of whether we need more teachers. Good food for thought.

Last week’s presidential debate revealed one area of agreement between the candidates: We need more teachers. “Let’s hire another hundred thousand math and science teachers,” proposed President Obama, adding that “Governor Romney doesn’t think we need more teachers.”

Mr. Romney quickly replied, “I reject the idea that I don’t believe in great teachers or more teachers.” He just opposes earmarking federal dollars for this purpose, believing instead that “every school district, every state should make that decision on their own.”

Let’s hope state and local officials have that discretion—and choose to shrink the teacher labor force rather than expand it. Hiring hundreds of thousands of additional teachers won’t improve student achievement. It will bankrupt state and local governments, whose finances are already buckling under bloated payrolls with overly generous and grossly underfunded pension and health benefits.

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.

Most people expect that more individualized attention from teachers should help students learn. The problem is that expanding the number of hires means dipping deeper into the potential teacher labor pool. That means additional teachers are likely to be weaker than current ones.

Parents like the idea of smaller class sizes in the same way that people like the idea of having a personal chef. Parents imagine that their kids will have one of the Iron Chefs. But when you have to hire almost 3.3 million chefs, you’re liable to end up with something closer to the fry-guy from the local burger joint.

There is also a trade-off between the number of teachers we have and the salary we can offer to attract better-quality people. As the teacher force has grown by almost 50% over the past four decades, average salaries for teachers (adjusted for inflation) have grown only 11%, the Department of Education reports. Imagine what kinds of teachers we might be able to recruit if those figures had been flipped and we were offering 50% more pay without having significantly changed student-teacher ratios. Having better-paid but fewer teachers could also save us an enormous amount on pension and health benefits, which have risen far more than salaries in cost per teacher over the past four decades.

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.

Educational technology is still in its infancy, but some amazing innovation has already happened, especially in higher education. Coursera allows students to take free classes from the best professors in the world. In K-12, charter schools such as Rocketship Academy in California and Carpe Diem in Arizona “flip” the classroom so that computers do much of the teaching and teachers are primarily tutors, problem-solvers, and behavior managers. This model could allow for much more individualized instruction with many fewer teachers.

Of course, this productivity-enhancing substitution of technology for labor is occurring outside of the public-school monopoly. Without choice and competition such as from vouchers and charter schools, there is little incentive for the traditional public school system to innovate or economize.

On this we see an important difference between the presidential candidates. Mr. Romney favors voucherizing federal education funds so that parents can take those resources and use them to send their children to schools of their choice. He also favors a decentralized approach that leaves policy decisions to state and local governments. Without federal mandates and subsidies, state and local governments are unlikely to drive over the financial cliff by hiring more teachers.

Mr. Obama, on the other hand, has a Solyndra-like solution. He’s happy to have the federal government pick the “winning” reform strategy of hiring another army of teachers by devoting federal resources to that approach. If it once again fails to improve student outcomes while stifling innovation, taxpayers will be stuck paying the bill.

Mr. Greene is a professor of education reform at the University of Arkansas and a fellow at the George W. Bush Institute.