The basic problem, before I go to far off topic, is that these schools have a high turnover rate for young and energetic but inexperienced teachers. They are driven, both by personal passion for their work and by the culture of their schools to work excessive hours - on a daily, weekly, and yearly basis. This level of work is impossible for most people to sustain given the intangible and often negligible benefits of their efforts - i.e., their personal gain (financial) is not commensurate with the level of effort, and the gains by their students are not much different than their more experienced colleagues working more efficiently. From Edwize:
The school hires energetic and well-meaning, but young and completely novice teachers. It then has to employ ‘teacher proof’ curricula and extend the ‘on time’ into the evening in order to compensate for the lack of teaching skill and experience. Teaching needs to be reinforced by a school culture which leans toward the authoritarian. By the time a teacher would ordinarily have begun to acquire the knowledge and skills that allow her and her students to work smart as well as hard, she has burnt out, and is unable to maintain the intensity of work. It is also impossible to start a family with such a work load.
I'm neither young, nor particularly energetic or bright, and I'm not working at a KIPP school, but I do teach within a school culture with a strong work ethic. And I am a bit overextended as I've mentioned in earlier posts. The pace of work that started the school year has not subsided, the demands of my job still have me working on average about 10-12 hours per day (5 days per week - I'm averaging in weekend hours) and a lot of it is precisely the inefficiency you would expect to find in new teachers - scrounging around for activities and labs, gathering materials for labs, setting up materials, creating quizes and tests that are appropriate for the regents curriculum, helping students make up missing work, etc. I can easily see myself next year chopping an hour or two off the average workday and at the same time being a better teacher.