[hugh3]

The problem is that teaching isn't a meritocracy. We talk about how hard it is to evaluate coder skill, but it's infinitely easier than evaluating teacher skill

The interesting thing is that students know perfectly well who the good and bad teachers are. And really, the school principals should know this as well... and if they don't know then they could easily find out just by sitting in on classes and looking at the students' work. It's not really a big problem for a boss to know how well his individual employees are doing, bosses do that all the time.

[jbooth]

Students do not know perfectly well who the good and bad teachers are. Adults with hindsight can discern the good and bad teachers but I can think of multiple cases where I had my good/bad flipped as a student compared to later on when I compared my knowledge level to other adults.

I had a writing teacher I didn't particularly like, then I got to a good college and found out I was one of the better writers. Turns out she was pretty damn good at her job.

[rapind]

The problem is that even the most astute principals can't do anything about their bad employees. They can only trade them off to other schools (and what do you think they get in return?).

Once a teacher has tenure it is almost impossible to fire them... and they know it. The concept of tenure in general isn't necessarily an issue, it's just an incredibly bad implementation (only takes 3 years! come on!).