My my last post had far too much vitriol for my liking, and I feel the need to cleanse my system with a less argumentative and more thoughtful post.
One problem in schools is that there are bad teachers who continue to harm students year after year. What do we do about these teachers? Well, fire them of course -- that's the easy answer.
Unfortunately, the solution is far from simple. Furthermore, the extent of the problem is maybe just as complex.
Let's start with the scope of the problem. How many bad teachers are there? What qualifies a teacher as "bad?" Are there more bad teachers than there are bad lawyers or accountants? Are teachers bad because they have no talent, put forth no effort, or because they attempt to harm students? I'm not sure that we have answers to any of these questions.
Assuming that there are a lot of bad teachers, the next question is why. Why are there so many bad teachers? Are the unions protecting them? Are principals failing to evaluate thoroughly? Do teachers tend to burn out? Do bad people try to be put in a position of authority? Are there no good teachers to replace them? There might be merit to theories that accompany all of these questions.
So, given that we (or at least I) don't really know how bad the problem is, how should we deal with the problem? Create better evaluation systems? Outlaw unions? Put more pressure on principals to evaluate teachers? Put more pressure on bad teachers? Give bad teachers more training? Fire them all?
I'm of the distinct opinion that there's no easy solution. That, of course, doesn't mean that we shouldn't try or should indefinitely delay action (any teacher that abuses a student, for example, should spend another second in the classroom). But I'll bet we'd be closer to an answer if people tried to answer all of these questions rather than just pushing a pet solution. In other words, it's likely that the solution is no simpler than the problem.
More questions inspired by comments: Would "bad" teachers be more effective in a different environment? When should "bad" teachers be filtered out?