The research is clear: Teacher quality affects student learning more than any other school-based variable (issues such as income and parental education levels are external). And the impact of student achievement on economic competitiveness is equally clear. That's why it's so disturbing that in 2010, the SAT scores of students intending to pursue undergraduate education degrees ranked 25th out of 29 majors generally associated with four-year degree programs.

The test scores of students seeking to enter graduate education programs are similarly low and, on average, undergraduate education majors score even lower than the graduate education applicant pool as a whole. Education schools long have accepted under-qualified students, then offered them programs heavy on pedagogy and child development and light on subject-matter content. But steps are finally being taken to improve teacher preparation programs and confront a problem that has for too long largely been met with denial.

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The University of Central Florida (UCF), the state's largest producer of teachers, exemplifies what's wrong with much of our system of teacher preparation. The Hechinger Report found that that only six of UCF's 65 programs gave out a higher percentage of A's and A-minuses than the School of Teaching, Learning and Leadership. Between the fall of 2011 and the summer of 2012, 73 percent of the grades the school awarded were A's or A-minuses. Compare that to electrical engineering, where such high marks accounted for 34 percent of grades, or the 40 percent of grades in the A range in food services and lodging management.

In an e-mail response, the university's spokesperson dutifully wrote that if faculty members do their jobs well "every future teacher demonstrates their competencies to the highest level and graduates with the knowledge and skills to become a highly effective classroom teacher." It's like Lake Wobegon: Everybody is above average.

But the fog of denial is beginning to lift. The American Federation of Teachers has proposed the equivalent of a bar exam that would require prospective teachers to demonstrate knowledge of their academic subjects and spend a year in "clinical practice" before sitting for the exam. The plan calls for education schools to raise their standards by requiring a minimum 3.0 grade-point average both to enroll and to graduate. Meanwhile, the Council for the Accreditation of Educator Preparation has proposed controversial new standards that would require teacher-education programs to prove that their graduates are raising their students' test scores.

And it looks like UCF's teacher-preparation program will have to step up its game. Florida is developing a rating system for education schools that covers six areas including student achievement and graduate employment and retention.

Making education schools accountable for the quality of their graduates goes hand-in-hand with holding the graduates of those schools to higher standards when they seek to move into the classroom. The Massachusetts Tests for Educator Licensure are far more rigorous than most of their counterparts in other states. When the Massachusetts tests were first administered in 1998, 59 percent of teacher candidates failed. Chaos ensued, but Bay State leaders didn't back down, and seven years later Massachusetts' public-school students began a streak, still intact, of finishing first in every test and on every grade level in the National Assessment of Educational Progress.

Culture change comes neither quickly nor easily. But given the link between teacher quality and student achievement in the larger context of a hyper-competitive global economy, it is a battle that must be fought. American teacher-preparation programs desperately need to move from a Lake Wobegon culture to one focused on excellence. Thankfully, it seems that this belated transformation is well underway.