This Washington Post article talks about Ed. Sec. Arne Duncan’s impact as schools chief in Chicago. Arguments can be made about the definition of success, or improvement, or change, but one quote has come to the attention of more than a few readers:
"Obviously, you always want to get better faster," Duncan said in an interview when asked about the federal math scores. "I was focused on outcomes — improving graduation rates, making sure that students who graduated had a chance to pursue higher ed. You can have the best test scores in the world, but if kids aren’t going that next step, you’re not changing their lives."
That is one danger of teaching based on standardized testing. Based on the metrics you are using, it is an useless loop. You establish a test to measure teaching, and then teach to improve the test. The measurement in itself is meaningless. You might as well be teaching to improve their height.