Education Change: Evaluation

As there is increasing conversation about teachers and their tenure, I looked to see how many of my former teachers were still teaching at the same school. While the majority of them were still there, it's not very surprising since I was lucky to have had many inspirational and passionate teachers unlike what I have read in articles about the overall status of the country's educational system. I was extremely fortunate in this aspect even in a public school system; I was lucky especially in middle school when my teachers realized I wasn't being challenged enough and moved me up a level. Unfortunately, this does not happen often enough.
But there are plenty of debate on how teachers should be evaluated. It is crucial to analyze teachers and their effectiveness to teach, but it must be done in a method where it won't impede their teaching plans. A few of my teachers changed the schedule and their teaching style during evaluation days, which I assumed was done in order to meet the evaluation criteria. In turn, this makes the teaching assessment utterly useless. I'm not a big supporter of standardized testing and using them to interpret a teacher's efficiency; I feel standardized tests can often constrain methods of teachings and is accompanied by too much pressure to teach to the test. I don't know what would be the best solution to this problem but I think a mixture of different assessments would be the best: trained evaluators to observe and have discussion with the teacher, testing results, and maybe even integrate student reviews (More meaningful with increasing age groups). With the increasing use of technology in schools, it can also be used to analyze a teacher's lesson plans and how the teacher is moving with the ever changing technology.
The most significant assessment of all has to be self-assessment. This is the teacher's responsible and should be a continuous process throughout their careers. This is the key to the most successful teachers and is driven by the dedication and devotion to help their teachers.
I've heard that many devoted and energetic young teachers have been laid off due to budget cuts because of the combination of lack years of experience and tenured teachers. I'm don't know the particulars of each situation but I'm sure there are some that are perfectly justified in terms of performance and what's best for the students. But tenure for teachers don't make much sense since we must ensure their effectiveness. I understand the purpose of tenure is to protect the teachers but there must be a mixture of job security and having the best group of teachers. With a high percentage of all teachers receiving tenure (90% and higher), the system for determining tenure isn't functioning correctly. We must remember that the most important goal is to teach/develop students to our best ability.