Some of the most important provisions of the federal No Child Left Behind Act are those requiring all teachers to be highly qualified -- not just certified but able to demonstrate content knowledge in the subjects they teach -- by the 2005-06 school year. That's an eminently reasonable goal, but also an especially ambitious one for the schools serving many poor and minority students, which today disproportionately employ teachers who aren't equipped to teach them to high standards.

The obvious answer is to raise teachers' pay. That's true so far as it goes. Teaching is a difficult job and many teachers are sorely underpaid for the long hours and hard work they put in. But simply raising teacher pay across the board, even where it's possible, will not do the trick. That's because "average" pay will not be enough to deal with shortages of qualified teachers in high-poverty schools and in certain subjects like math, science, and special education. Students in these schools and in these subjects are least likely to get a highly qualified teacher.

The problem is that most states and school districts are still locked into a one-size-fits-all system that rewards teachers for their degrees and seniority, but rarely takes into account the difficulty of teaching assignments, or the supply of and demand for different types of skills and knowledge. Not only is this system out of sync with the way most professionals are paid today; it's wholly unsuited to ensuring that the neediest students get the best teachers.

It doesn't have to be this way. In a paper released earlier this year by the Progressive Policy Institute, education analyst Bryan C. Hassel laid out a compelling case for greater differentiation in teacher pay, taking into account factors such as challenging assignments, scarce skills or knowledge, and actual performance on the job. Hassel noted that a number of states, school districts and charter public schools -- whose own funding is dependent on educational results -- are experimenting with a diverse array of innovations in teacher pay. And like charter schools themselves, differential pay appears to be very attractive to talented young teachers, who prefer flexibility and the opportunity to excel. While these teachers might not speak with the loudest voices in the policy debates because they're less likely to be active in national organizations, they are the ones who are most important to attract and retain right now.

You'd think that these ideas would be non-controversial -- after all, most high school students understand the laws of supply and demand. However, those elements of the education establishment with a vested interest in a top-down, command-and-control model for teacher pay vociferously fight efforts to modernize teacher compensation.

Differential pay is not an alternative to raising teacher salaries overall -- it's something we need to encourage whatever the general level of teacher salaries. Moreover, the public will be much more willing to support higher salaries generally if they see serious reforms succeed in the toughest and neediest schools. It's a holiday resolution everyone should accept on behalf of the neediest students: putting a little something extra under the tree for their teachers.