I'm curious. Why do you think tests show how well a subject is being taught? In my experience, tests distract everyone from the subject matter. Both students and teachers are more interested in test scores than they are in the subject matter. They memorize factoids and procedures in order to take a test, then they forget it all so they can get on with the memorization for the next test. The only people who can learn anything (except for how to take a test) in that kind of environment are the ones who test so well that they don't have to worry about the tests. They have the time to pay attention to the subject matter (often on their own because the class time is so frequently being used for test prep). I've known many students who had only the vaguest idea what a course had, ostensibly, been about by the next semester. They were certain that schooling was about test-taking, and that the different subjects were only used to keep the tests from all being the same. No joke.