Tests are the only objective way to measure student performance.
Edit: at first I was just playing devil's advocate; now I completely support this mechanic of creating standards and holding the education system accountable to them. Someone convince me this is a bad idea.
Well, yes and no. This is to make it easier to evaluate teachers without actually spending money to go out and evaluate them.
Flaws with this method:
A) I assume these would be standardized tests, and not actual test scores in the class. First off, that means students will be more stressed and some may perform more poorly on tests.
B) Guessing would completely mess with the results, considering American tests, especially standardized ones, tend to all be multiple choice.
C) This doesn't actually test how good the teacher is, just how much the students learned. I had a teacher in 8th grade who only showed movies, which, while we watched she would either drink in class (She filled her coffee mug with vodka but apparently we weren't supposed to know that) or went out to smoke. That being said, the textbook and movies gave us all the information we needed to pass the ridiculously easy tests they give in that year. Should this teacher stay on the staff because her students get decent test scores? (I have more examples, if necessary.)
D) As someone said, this encourages teachers to turn a blind eye on cheating. (I already had one teacher my freshman year who, since he was a horrible teacher and as a result students didn't learn anything, and as a result got bad grades on his rather difficult tests (Basically what would have been a normal test if we'd actually even once mentioned the material on them), would ignore cheating so that the class average would reach an acceptable level.)
E) I would assume these would be, like the SATs, ACTs, etc., one or several nationally administered tests? If so, then that sets really unfair standards due to how rich or poor a school is.
F) If I have been wrong, and these are based on test scores of tests given by the teachers themselves, then the flaw is obvious: If the teacher wants a good grade, administer a ridiculously easy test. This would make the bill have the opposite effect of what was intended, and actually hurt the students' educations.
Arg, I actually forgot some of my points as I realized new ones... I'll add more if/when I remember them.