If our kids learned as much in school as Canadian kids do, we'd increase our gross domestic product by about $50 trillion over the next 80 years, estimates Eric Hanushek of the Hoover Institution.

The GDP gain would be doubled if our kids learned as much as Finnish kids do, he said. The average yearly gain would be enough to wipe out our $1.2 trillion federal budget deficit.

"The achievement gap between the U.S. and the world's top-performing countries can be said to be causing the equivalent of a permanent recession," Mr. Hanushek wrote for Education Next.

Not so many years ago, our schools were the best in the world. But in the Organization for Economic Cooperation and Development's rankings in 2010, the United States was 17th in reading, 22nd in science, 29th in math. In every other OECD country, 25- to 34-year-olds are better educated than 55- to 64 year-olds. But not in the United States. Today we lead the world only in how much we spend per pupil.

Most of the top performers in the world are Asian. Asian kids study a lot more than ours do. But Finnish students perform almost as well as the best Asian students. In the 1970s, the Finns were below where we are today. The poor performance of our kids can't be blamed on ethnicity or culture.

Far and away the most important factor in student learning is the quality of teachers. If we got rid of just the bottom 5 percent to 7 percent of teachers, that alone would lift our kids to Canadian levels, Mr. Hanushek calculates.

Our teachers "do not know anything," according to Terrence Moore, who teaches history at Hillsdale College. That's largely because most have degrees in education rather than in the subjects they teach.

"Colleges of education are considered vast wastelands of mediocrity at most comprehensive universities," wrote Richard Vedder, director of the Center for College Affordability and Productivity, in the Chronicle of Higher Education. "Future teachers are better served by getting good grounding in academic subject matter."

Ed schools seem to think knowing stuff isn't important.

"If you confront [teachers] with the fact that they, just as their students, can tell you nothing about the first 10 presidents or the use of the gerund, they will blithely respond that it is not so important for them to know things as to know 'how to know things,' " said Mr. Moore.

Students learn more quickly from teachers who make learning fun. But if a teacher lacks knowledge, it doesn't matter how good are his or her communications skills or how much he or she cares about the kids.

"Students learn a lot from the teacher who knows a lot," Mr. Moore said. "They learn nothing from the teacher who knows nothing."

Furthermore, "most of the good research on learning, educational costs, etc., is being done outside education schools by psychologists, political scientists and economists." Mr. Vedder said. Ed schools, he concluded, are "a blight on true higher education," so state governments should consider defunding students in colleges of education.

The reform needed is to remove state "certification" requirements. The reason for them, we're told, is to guarantee that only the qualified teach. Their real purpose is to keep the knowledgeable out of the classroom.

In public high schools, 60 percent of students studying the physical sciences are being taught by someone who didn't major in the subject or isn't certified to teach it. The gap could be filled by retired or laid-off engineers. Few know more biology than a medical doctor, more about civics than a politician. But in many cases, if they haven't taken a slew of ed courses, they aren't allowed to teach.

Relatively few teachers get certified without going through one of the nation's education schools. "Yet these education schools," Mr. Moore points out, "not only do not impart real knowledge of academic subjects; they are actively hostile to it."

The dreck taught in ed courses can be as much a deterrent to professionals contemplating a career change as their cost, or the time it takes to complete them. Imagine Marxism dumbed down so much Karl Marx himself would run screaming from it in embarrassment.

If instead of being forced to hire the certified, schools were free to hire the qualified, colleges of education would wither away -- and learning would blossom.