The problem with standardized testing is not that they don't measure the progress well but that they measure all other sorts of confounding variables. Each standardized test has a small number question templates, and if the students familiarize themselves with the question templates they will do better on the tests, for example. Another important factor is timing: some standardized tests have a fixed amount of time allocated to a student, and hence there are many different ways of pacing yourself that lead to better or worse scores. Yet another important factor is the choice between open-ended and multiple-choice questions, and even the balance between these can be learned.

So every standardized test has some confounding variables, and effort spent teaching the students to do better on the tests by dealing well with these variables is effort that does not go towards helping the students learn the material. If the standardized tests are known and used to evaluate the teachers the incentives suddenly get really strong to teach to the test by focusing on the idiossincrasies of specific testing schemes over teaching the actual subject.

Standardized tests are a great way to measure performance and improvement but only if the results won't be used for decision-making, otherwise it creates an instant incentive to game the system.

It's quite possible to write tests that fairly accurately measure the basic material to be taught in the third grade. Well written tests cannot be 'gamed' to any significant degree. People have known how to write good tests for over 50 years and have often done so.

Heck, when I was teaching in college, I passed out copies of tests from earlier semesters. Then the students could study just to the tests and try to 'game' them. Still, had to know the material at least to some degree to do even that. Net, the students had every opportunity to study just to the tests and I was in effect teaching just to my own tests and still the students had basically to learn the material.

Standardised tests should be used to collect data, but failure to score well on standardised tests shouldn't be punished. Otherwise you just give everyone an incentive to game the metric, and quality disappears.

Nonsense. For basic material, as in K-12, people have known how to write good tests for over 50 years and often have. The concepts of reliability, validity, separation, difficulty have all been polished at least since 1950, maybe 1930.

That the tests are not reliable and valid measures of learning and can easily be significantly 'gamed' and, thus, should not be used to evaluate K-12 teaching is just an unsupported myth being put out by propaganda of the AFT and NEA to protect bad teaching.