Still waiting to move up in the library queu to read Outliers, but I've enjoyed this discussion. I came across this article written by the author Malcolm Gladwell in the New Yorker:
Most Likely to Succeed: How do we hire when we can�t tell who�s right for the job?
It likens the search for good teachers to the search for good quarterbacks. http://www.newyorker.com/reporting/2008/12/15/081215fa_fact_gladwell
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After years of worrying about issues like school funding levels, class size, and curriculum design, many reformers have come to the conclusion that nothing matters more than finding people with the potential to be great teachers. But there�s a hitch: no one knows what a person with the potential to be a great teacher looks like. The school system has a quarterback problem.

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Teaching should be open to anyone with a pulse and a college degree�and teachers should be judged after they have started their jobs, not before. That means that the profession needs to start the equivalent of Ed Deutschlander�s training camp. It needs an apprenticeship system that allows candidates to be rigorously evaluated. Kane and Staiger have calculated that, given the enormous differences between the top and the bottom of the profession, you�d probably have to try out four candidates to find one good teacher. That means tenure can�t be routinely awarded, the way it is now. Currently, the salary structure of the teaching profession is highly rigid, and that would also have to change in a world where we want to rate teachers on their actual performance. An apprentice should get apprentice wages. But if we find eighty-fifth-percentile teachers who can teach a year and a half�s material in one year, we�re going to have to pay them a lot�both because we want them to stay and because the only way to get people to try out for what will suddenly be a high-risk profession is to offer those who survive the winnowing a healthy reward.