[Sanders' study is part of] the ongoing search for the characteristics of the effective teacher. A definitive list of such characteristics is the holy grail of teacher policy. If we only had that list, so the thinking goes, we could do all kinds of important and useful things. We could reshape education schools to impart those characteristics. We could set up certification systems to filter out teachers who don't have those characteristics. We could design compensation systems that pay teachers with those characteristics more money.... My strong suspicion is that this whole way of thinking will ultimately turn out to be profoundly wrong.... [W]e could double, triple, or magnify tenfold our efforts to refine and expand things like the NBPTS and still never get close to identifying the effective teacher, for the simple reason that she doesn't exist.That reasoning conflates screening instruments with teacher education and professional development, and it fails to address the fundamental weakness of much of this research, the search for a general qualification of teachers based on a global credential (not usually immutable characteristics). Then Carey went into some weird stuff about Dell's reversal of the usual production-before-sales process. (Never mind that car customers who were willing to wait could custom-order cars years before.) I think it has something to do with being satisfied with identifying effective teachers and not worrying about helping teachers (and prospective teachers) get better. Maybe I'm misreading that entry, but it sure sounded like that.
And, if so, Carey is wrong. Suppose we could identify with 100% accuracy who the good math teachers are. (Incidentally, neither Bill Sanders nor I will ever claim this, regardless of our differences otherwise.) Do we then fire those who are weaker and pray that their replacements are better, on average? As far as I'm aware, there has never been a period of time when you had 100% perfect teachers, when a system didn't need to work with the teachers they had because, well, they were the teachers there at the moment. It makes no sense from a decency, fairness, civil rights, morale, or human resources standpoint to sit there and let an inexperienced, less-skilled, or overwhelmed teacher flounder just because the research on national certification or masters degrees isn't conclusively in favor of those as screening/pay increment policies.
In my own research on special education history, there are several points (including today) when administrators have griped about the lack of trained specialists. The expansion of special education meant that there has always been a shortage of specialists, and often regular teachers were pulled into special education. Lo and behold! these "retreads" (as one former Peabody College professor termed them) were pretty sharp folks and were able to learn new tricks just fine, thank you (again, to the pleasant surprise of my informant). To borrow from a certain Crosby, Stills, Nash, & Young classic, if you can't have the ones you want, help the ones you have. They'll probably be just fine.