Ray Fisman asks that question over at Slate.

My answer is that the problem has less to do with hiring good teachers and more to do with difficulty (thanks to teacher’s unions) with firing bad teachers.

Anyone who has ever done any significant amount of hiring can tell you that every hire is a roll of the dice.  Sometimes you’ll hire someone with an impressive resume, great interview skills and positive references and they’ll turn out to be a dud.  Other times you’ll hire someone with a checkered employment history and a less-than-stellar resume and they turn out to be one of your best employees.

What is most important to developing a good work force is not hiring decisions (though that’s a big part of it) but rather the ability to weed out employees who aren’t working so they can be replaced with someone better.  It’s a trial-and-error process.  Sometimes good employees can let their performance slip.  Sometimes bad employees can improve their performance.

Either way, management has got to be able to effectively remove those who aren’t working well and replace them with those who will.  If management can’t do that they can’t get rid of bad employees, and good employees have little incentive to keep performing.

Teacher unions have for years been throwing roadblocks in the way of school administrator’s ability to fire bad teachers.  Which is why many of America’s schools routinely perform below par.

Want better teachers?  Make it easier to fire bad teachers.