There has been a big push in recent years towards more standardized testing in schools. Parents demand that their children be taught the basics (Cue the speeches about how bad this latest generation is) and everyone wants more accountability and information. Which students suck? In what areas? What other demographics contribute? The end result of this desire for information is huge countrywide tests that end up warping the entire system of education. Some teachers in the US have actually started a mass protest against the tests and are refusing to implement them, to which I say hooray!
There are uses for mass testing but as one Larry Smith repeatedly shouted "What is the cost?" The cost, it turns out, is a lot. Standardized tests cost a ton of money to administer from creation to administration to marking. They also lead to incredibly foolish things like basing teacher pay on test results and students picking schools on the basis of standardized test scores. Do we want teachers to ignore the teaching of emotional intelligence, cooperation, and other life skills entirely while they focus only on the topics covered by the test? No! The kids end up being good at taking a particular kind of test which is useful for precisely NOTHING.
We know that test scores correlate very well to later test scores. They also correlate very well to virtually nothing else of note. I can tell you this for certain as I was particularly good at taking tests and that skill only taught me that I didn't need to actually learn anything. If you ask any employer what they want in an employee and give them the choice between someone with good test scores in grade school and someone with better discipline, social, and organizational skills they will take the second every damn time. This is becoming more and more true in a world where every random thing in the universe is on wikipedia; what use are facts and memorization compared to the ability to USE those facts for something worthwhile?
Good teaching is something we all know when we see it but have a hell of a time writing down specs for. Just like defining what exactly pornography is and is not we could spend years sitting around arguing about it while nearly everybody can pick it out in an instant. Though we quite reasonably want our teachers to be of excellent quality we simply have to accept that we have no consistent, transparent, objective method of determining that. Maybe someday we will develop such a metric but it certainly isn't "whoever gets the kids to score well on this particular test".