I had some time over the holidays to catch up on all of my New Yorker magazines, and I came across a fantastic article written by Malcom Gladwell, author of The Tipping Point, Blink and most recently, Outliers. The article is titled "Most Likely to Succeed: How do we hire when we can't tell who's right for the job?" (Click here to read it.)

(If you do read it, you'll note that Gladwell spends a lot of time discussing finding the right quarterback for an American football team. Ignore those parts, or skip them, or whatever. They're not necessary for the the rest of the article, and they're boring. Even I don't care about American football...)

Gladwell's premise is that you can't tell whether a teacher will be good when you hire him or her. The new teacher may have gotten good marks as a trainee, and they may have performed extremely well at university. Yet you don't know if the person is an effective teacher until you get him or her into a classroom, interacting with students, and can watch the teaching and measure the learning that is occurring.

At that point, however, you may be too late. The most startling statistic in this article, and one that I think every government official and education policymaker around the world should read is this:

Eric Hanushek, an economist at Stanford, estimates that the students of a very bad teacher will learn, on average, half a year's worth of material in one school year. The students in the class of a very good teacher will learn a year and a half's worth of material. That difference amounts to a year's worth of learning in a single year.

And for you parents out there...think about this when considering your child's school:

Teacher effects dwarf school effects: your child is actually better off in a "bad" school with an excellent teacher than in an excellent school with a bad teacher.

Finding good teachers is a problem that is nearly universal. Finland is the only country I've visited where the competition to become a teacher is so fierce that truly the best of the best are the only ones to make it into a classroom. So what are the rest of us doing? Why can't we train, identify and retain high-quality teachers? To follow on from that, why is it so difficult for schools to improve bad teachers - or get rid of them altogether? A successful company wouldn't keep someone on board who isn't doing their job year after year. Why are we allowing people like that to teach our children?

I know the short answers to all of the questions above, but I just don't understand why things can't change. I invite you to agree or disagree with me.