I am all for teacher accountability. But measuring how well a teacher does by looking at one test a year is not the way to do it. There are many problems with this system.
1. The bad day problem: Most of us watch sports. There are days when you just excel and then they are days when you can do nothing. We never know what day we are going to get even if we do the right things like eating a good breakfast and getting enough sleep. The test is really just a snapshot of a day. We have all taken bad and good pictures. Sometimes it is the person behind the camera, sometimes it is the person in front of the camera.
2. The incentive problem: There is no incentive for the student to do well or even try on the test. There are no repercussions for them if they do not do well. Most students have pride and want to do well on it. Many students in my population do not like the test. They tests make them feel "stupid." (Believe me I have heard this refrain many times. They have stopped trying to take the test. Some speed through it as fast as they can. Some make patterns. Some just randomize answers. Some try for a while til they get frustrated. Some try the entire time. I have tried food bribes and other incentives for them to try the entire exam. Sometimes it is successful; most times it is not. In the big picture, i do not think this is a major of serious problem but in my population I think it is.
3. Required Test: The students are not required to take the test. Parent have the option of having their kids not take the test. This could lead to all sort of problems should the test me the marker of teacher performance.
4. Teaching to the Test: There are definitely strategies to taking a multiple choice test. I loved math tests. I really enjoyed the fact that most problems did not require me to actually complete the problem. I could find the answer based on those given by doing a little work. I also know what type of answers they would provide. They always give an answers that will fit the common mistake such as a negative answer when the answer should be positive. Eliminate those and your chances go from 20% to at least 25%. Find another simple thing to eliminate before you do any work and your odds keep getting better. Where was the academic value in what that I just gave you?
5. One Size Fits All test: Sure they are standardized. But it just means it fits most. So you can get most people in it but there will be many that it does not fit well. There is a reason why we have so many choices in our life because we all like and are comfortable with different things. My one size fits all beanie is a little short and does not cover my ears all the way. Options on testing is the way to go. Mastery of knowledge can be expressed in many ways. To force us to use only one is not the way to go.
I am tired of this rant but I am sure I could find more problems with this method of measuring teacher progress. How about the student who does not like the teacher and intentionally tanks to get back at the teacher. Hmm, I like that one. I wonder if I can use it for ill actions.