Union collective bargaining agreements often complicated matters by stipulating rules that made honest assessments of teacher performance difficult, if not impossible.
Some stipulate that classroom observations must be done on schedule, so teachers can be ready to put forward their best effort on that day.
Some contracts say administrators cannot use video equipment to observe teachers without their knowledge, as if it's somehow unfair to watch a teacher at work, doing what they generally do when they don't think administrators are watching.
A lot has changed in two years. In addition to D.C. public schools, 17 of the 23 states that link student learning to teacher evaluations do so in a significant way, according to the NCTQ report.
The states that make student achievement a major part of teacher evaluations include : Arizona, Colorado, Delaware, Florida, Idaho, Illinois, Indiana, Louisiana, Maryland, Michigan, Minnesota, Nevada, New York, Ohio, Oklahoma, Rhode Island and Tennessee, as well as D.C. public schools.
Eleven New Jersey school districts have begun implementing a pilot program that could lead to teacher tenure and pay being linked to student outcomes, reports NJSpotlight.com.
But the teacher unions still wield considerable power in all three states - Connecticut, New Mexico and New Jersey - that are close to making evaluation changes, making success far from a sure thing.
Paul Gessing, president of the Rio Grande Foundation, said that while teacher evaluation reform will be on the agenda when New Mexico's legislators convene for the upcoming 30-day session, it'll be "a tall order to get it done."
"New Mexico is resistant to any reform, even though we're 49th in almost everything, including graduation rates," Gessing told EAG.
Gessing said the state legislature is controlled by Democrats, who are mostly controlled by the teacher unions. As a result, "Everything here happens at a snail's pace," he said.
Obama's 'Race to the Top' credited for new reforms
In its recent "State of the States" report, the NCTQ writes that tying student learning to teacher performance "marks an important shift in thinking about teacher quality" - away from teacher qualifications and toward "their effectiveness in the classroom and the results they get with students."
NCTQ credits President Obama's Race to the Top initiative for motivating states to rethink the evaluation process.
"The 2010 federal Race to the Top (RTTT) competition spurred unprecedented action among states to secure a share of $4 billion," the report reads. To qualify for federal funds, states had to devise in-depth plans for improving their K-12 systems, many of which included new teacher evaluation systems at least partially based on student test scores.
The federal government is currently offering another reform incentive to states. States can apply for waivers from No Child Left Behind benchmarks in exchange for reform commitments, including how teachers are evaluated.
That's happening in the Kentucky legislature, which seems likely to approve a bill that would standardize how teachers are evaluated throughout the state.
The bill's sponsor, State Rep. Carl Rollins, a Democrat, said he supports basing 30 percent of a teacher's evaluation on student achievement.
Unions support changes?
With the public generally supportive of accountability-based teacher evaluations, the nation's two largest teacher unions are eager to be seen as cooperative.
"Sadly ... we once again hear this myth about the union standing in the way of performance," wrote Randi Weingarten, president of the American Federation of Teachers, in a recent letter to the New York Times.
Weingarten urged lawmakers to find a way "to fairly evaluate" teachers.
Last summer, delegates to the National Education Association's annual convention voted to adopt a new policy that acknowledges student performance a legitimate part of the evaluation process.
"What it says is, now we are willing to get into that arena," NEA President Dennis Van Roekel said. "Before, we weren't."
But look past the agreeable rhetoric and it's clear that the unions don't believe it's possible to incorporate student achievement into evaluations in a fair or scientifically valid way.
"We believe that there are no tests ready to do that," Segun Eubanks, the director of teacher quality for the NEA, told the New York Times.
Bottom line: The national teacher unions support performance-based teacher evaluations in theory, but not in practice.
The unions' double-talk may not matter, in the end. Lawmakers in both parties seem committed to these reforms, and this trend seems destined to keep growing.