Harvard's Jal Mehta writes in the NYT:
By these criteria, American education is a failed profession. There is no widely agreed-upon knowledge base, training is brief or nonexistent, the criteria for passing licensing exams are much lower than in other fields, and there is little continuous professional guidance.
It is not surprising, then, that researchers find wide variation in teaching skills across classrooms; in the absence of a system devoted to developing consistent expertise, we have teachers essentially winging it as they go along, with predictably uneven results.
Read the whole thing.