Hiring teachers is an art, not a science. Once a teacher is hired, if he/she can't do the job, evaluate them, document the problems, then fire 'em. It isn't necessary to enter into a protracted remediation effort to save a poor teacher--who wants a retread teacher teaching their kids? The only mistake is in not firing the bad ones.

Contrary to the belief of many people, tenured teachers can be fired...as a former Superintendent of Schools, I have done it a number of times.