Indeed, this year's MetLife teacher satisfaction survey, the 28th such assessment of teacher, parent, and student perspectives on how school life is going, shows the impact of these conditions. Teacher job satisfaction has dropped 15 points since 2009, from 59 percent who were very satisfied to 44 percent, the lowest level in over 20 years. The percentage of teachers who say they are likely to leave the profession has increased by 12 points -- from 17 percent to 29 percent -- now nearing a third of all teachers.

Much has changed in those two years; in 2009, the impacts of recession-based cuts had yet to fully hit schools. Larger classes; laid-off colleagues; cuts to libraries, physical education, foreign languages, arts and music; and reductions in supports like health care, counseling, and afterschool programs that help low-income students overcome impediments to effective learning -- all factor into teachers' decisions about whether to stay on the job. Teachers, parents and students surveyed all reported rising levels of economic insecurity, hunger, poor health, homelessness and anxiety over lack of sufficient resources to pay for household basics. In my own region of Northern California, child homelessness has increased by more than 30 percent in the last two years, with some districts seeing more than 1 in 10 of their students without homes.

At the same time, public discussion and policy increasingly place the full weight of these problems on teachers alone. Despite repeated warnings from leading scholars that test-based "value-added" ratings cannot be reliably used to evaluate individual teachers because they reflect home and other school factors as much as the teacher him or herself, more states are urging that they be used to fire and reward teachers. This is particularly problematic given evidence that teachers' ratings decline when they teach the neediest students -- especially new English learners and students with disabilities.

Indeed, New York State's new policy effectively makes continuing to teach contingent on such test-based ratings, and New York City recently insisted on publishing teachers' names alongside their ratings. This created a furor as it became clear that the scores are wildly unstable from year to year and across subjects, are often based on inaccurate data, and appear unrelated to the known successes of good teachers or the failings of poor ones. This is prompting many great teachers to make plans to leave a profession they loveand children who need them.

Bill Gates noted in a recent op-ed in the New York Times that "using employee evaluations to embarrass people," is something a smart firm like Microsoft would never even contemplate, "much less publish in a newspaper." Even if it is legal, he points out, "as a harbinger of education policy in the United States, it is a big mistake," because "the surest way to weaken [systematic teacher development] is to twist it into a capricious exercise in public shaming."

The problem is not only that the ratings are poor measures of actual effectiveness, but that such policies fundamentally misunderstand what drives teachers to improve and to stay in tough jobs. In his recent best-seller Drive, Daniel Pink draws on years of research to confirm that the personal satisfaction of getting the job done right -- in this case, teaching students well -- is at the core of our drive. That's why bonuses handed out to teachers based largely on test scores turn out not to improve achievement and are often resisted by teachers who want support to succeed, not bribes that undermine intrinsic motivation and collaboration.

We have never heard more policy rhetoric about the importance of developing, recruiting, and retaining strong teachers, especially in our most troubled schools. Ironically, our policies have also never done more to ensure that good teachers will have little incentive to serve and stay in those schools. We need to get the incentives right. According to the Met Life survey, that means enacting a Broader Bolder Approach: treating teachers as professionals, providing them with opportunities to learn with one another and improve their practice, ensuring that schools offer decent teaching and learning conditions, and supporting children with the services that enable them to be ready to learn each day.