WE ALL remember our favorite teachers. We probably don't know anything about their education, certificates, or years of teaching, but we know they had qualities that made us remember them and what they were trying to teach us. My favorite teacher was a high school Latin teacher and debate coach. When my debate partner and I unexpectedly made it to the state finals, I woke before dawn to see Ms. Parks sitting on an Austin hotel room floor in her nightgown, poring through the debate material one final time in order to find any useful bit of overlooked information for us. I heard similar stories from students who testified at public hearings held throughout the country in 2004 by the Public Education Network (PEN) and local partners as they sought to find out what people thought of No Child Left Behind (NCLB). Few students knew much beyond the law's phrase of qualified for every classroom. Yet they could be quite candid, if not brutally honest, in describing teachers they considered highly qualified -- and those who were not. It was the teachers who took extra time with them, who taught the material so that I remembered it the next year, who made the content clear and attainable, that they considered good teachers. The students had no patience with teachers who wasted time or didn't know how to teach the material. One unforgettable bit of testimony came from a high school sophomore from the South Side of Chicago. He thought his algebra teacher was excellent and demanding. And for that teacher's classes, he noted, everyone shows up on time. Then the young man described the following period: A snooze fest with a teacher who acts like a spokesman for the Clear Eyes commercials. Half the students fall asleep. The idea that lack of paper certification might mean that the algebra teacher would be dismissed and the Clear Eyes teacher retained simply horrified this student. NCLB's emphasis on seeing to it that all classrooms are staffed by highly qualified teachers is commendable. Teacher competence is the most important factor in student learning. The ability to define that competence had been gradually emerging from research and policy making before NCLB, but the law, unfortunately, is loosening our grasp on a consensus about what it means to be highly qualified. This is one of those ideas -- like several others discussed previously in this column - - that is being left behind. The U.S. Department of Education has allowed states to describe loosely how they are responding to the statute on highly qualified teachers, which was itself loosely worded. NCLB requires states to pass that information on to parents and communities -- though this requirement seems to have been carried out only sporadically -- but all people seem to know is that almost all teachers have been certified as highly qualified. For an interim period, fewer teachers are passing the paper certification at the middle school level because subject-matter background has not often been required of teachers through the eighth grade. Highly qualified teachers, according to NCLB, must have a standard license, possess a degree in the subject they are assigned to, or have successfully passed tests in the subjects or met some other standard set by the state. For example, a state could declare a certain number of years of teaching as meeting the requirement (as many states have). According to an article in Education Week, the law does not guarantee that a state will emphasize content knowledge as the most important standard. At the same time, the law's endorsement of alternative certification does not guarantee that new teachers will have the background in pedagogy necessary to teach a subject well. Slipping to the back burner are many years of effort to build a definition of teacher competence through performance standards. …