Standardized tests
claim to measure those quantities. To be fair, my school system was quite good, so I don't think I suffered too greatly from teaching to the test, but I did read quite a few of the study/test guides put out by Kaplan and their ilk. Much of it was tricks based on the structure of the tests; the "types" of question that will be asked and type-specific solution strategies. These tests are not about basic understanding and skill at adding, reading comprehension, etc., but rather a well-defined subset of those skills. The assumption is that skill in the subset is a good proxy for fundamental skills in the student. If teachers are evaluated solely by these partial measures, it is in their best interest (and, in the eyes of the administrators, produces the best results) if they optimize for these partial measures; the argument from standardized testing opponents is that teaching for these partial measures has not been shown to produce general understanding.
In that sense, NCLB created a race to the bottom; schools that performed below-average got less funding, so if any schools successfully "taught to the test", they all had too or face budget cuts (that's my understanding, IANAT).
Is there evidence that these partial measures reveal and/or necessarily lead to a more general understanding?