From a very basic standpoint, it would seem that the titular statement in this post is just common sense. But it is clearly not that easy for a number of reasons, first, there is the notion that many times, a principal or school system doesn't know they are getting a bad teacher until well after the hiring decision is made. Second, once in a system, it is often hard to get rid of bad teachers for contractual and due process reasons. Third, there is constant turnover in the teacher ranks for a variety of reasons which requires the constant influx of new teachers. Fourth, recent legislative changes in the states mandating smaller class sizes has swelled the need for more teachers.
Over at Slate, Ray Fisman takes a look at the problem. Like most of these stories, he starts with a "case study":
PS 49 in Queens used to be an average school in New York City's decidedly below-average school system. That was before Anthony Lombardi moved into the principal's office. When Lombardi took charge in 1997, 37 percent of fourth graders read at grade level, compared with nearly 90 percent today; there have also been double-digit improvements in math scores. By 2002, PS 49 made the state's list of most improved schools. If you ask Lombardi how it happened, he'll launch into a well-practiced monologue on the many changes that he brought to PS 49 (an arts program, a new curriculum from Columbia's Teachers College). But he keeps coming back to one highly controversial element of the school's turnaround: getting rid of incompetent teachers.Now it would be very easy to sit and blame teachers unions (and I have from time to time) for putting roadblocks in the way to eliminating bad teachers. Likewise I would be very easy to blame principals and school systems for hiring bad teachers at the outset. But a school system has two competing interests to balance and woe unto the school superintendent who does not hire enough teachers to start the school year as the political and parental lashing is brutal in the extreme. Finally, it is very easy to blame the education schools for producing such a poor quality graduating class year in and year out.
Firing bad teachers may seem like a rather obvious solution, but it requires some gumption to take on a teachers union. And cleaning house isn't necessarily the only answer. There are three basic ways to improve a school's faculty: take greater care in selecting good teachers upfront, throw out the bad ones who are already teaching, and provide training to make current teachers better. In theory, the first two should have more or less the same effect, and it might seem preferable to focus on never hiring unpromising instructors—once entrenched, it's nearly impossible in most places to remove teachers from their union-protected jobs. But that's assuming we're good at predicting who will teach well in the first place.
To be sure, every one of those groups shoulders some of the blame for the cohort of bad teachers in America. While the group of bad teachers really is a small percentage of the teacher corps, the real problem is policymakers, or more precisely, the think tanks and interest groups that pressure policymakers into taking actions which lack verifiable substance and produce actual learning gains in the classroom. Perhaps no other educational policy has altered the teaching labor market than the push for smaller class sizes.
From a purely logical standpoint, having a smaller class size means fewer students per teacher and more teacher time per student. But as I pointed out several years ago, such a model assumes that you have teachers of relatively equal quality, a position we know that is false, not only from a statistical standpoint, but from a anecdotal standpoint, i.e. we all know teachers that are of better quality that most and teachers that are of lesser quality than most (and it doesn't matter how you define quality). Smaller class sizes, while it looks good on paper, doesn't necessarily mean that the resulting outcome for students will be better. In addition, there are other significant budgetary consequences for schools and school systems.
But when you have mandated smaller class sizes the larger number of teachers puts a downward pressure on wages, i.e. there are more teachers out there, there is a finite budgetary resource to pay said teachers, therefore smaller wages. You then get the constant argument that teachers are under paid, despite some evidence that the "lack of competitive pay" myth is pure bunk in at least one county in Maryland and probably a significant portion of the United States as well.
The pressure that society has pushed, as a result of interest group politics-i.e. teacher unions and other think tanks that believe smaller class sizes is the answer to improve education, to get smaller class sizes has, to a significant extent, exacerbated the poor teacher problem. With more teachers, you get a larger number of bad teachers, even if as a percentage the bad teacher problem is less. (If you have 3 million teacher and one percent are truly bad teachers, you have 30,000 truly bad teachers. If you have four million teachers and only .9 percent are bad teachers, you still have 36,000 bad teachers.) It is highly unlikely that any state legislature or school board is ever going to reverse the policy of small class sizes. You could get a change of "targeted class size" from 18:1 to 20:1, but even that is unlikely.
So the solution is going to be improve teacher quality at the start of the process, i.e. through the better professionalization of teachers. But the school boards and the Unions (they do have an interest, or should have an interest, in making the teaching profession of higher quality) will need to work out some way of getting bad teachers out of a classroom.
Sure, we could simply tell our schools to stop hiring bad teachers and oh were it that simple. The fact is that America has to learn itself that teachers are one, but vital, part of the educational sphere. We have to learn that we cannot, and should not, expect our teachers to be 1). social workers, 2). psychologists, 3). glorified babysitters or 4). responsible for our children beyond their education and safety at school, and that among all the other areas we have come to expect teachers to do. In short, our "problem" with bad teachers is a creation of our own political and social shortsightedness.