Improving Instruction through Evaluation?

This semester I'm teaching "Evaluator Approval:  Improving Instruction" at the University of Northern Iowa, as an adjunct.

So here's my question:  can a principal improve instruction through the standard teacher evaluation process?

Here are some of the issues:
Teacher A tells me: "Evaluations do no good unless the people being evaluated are given specific help for the specific problems noted. My evaluations were always good, but they didn't help me become better....I don't mind a criticism if the critic can explain how or why something else would work better. I do mind it if they just make a statement that gives me no help and nothing to work on."

Teacher B tells me their concern: "when the administrator tells you what they expect, but they've never had to do it except in isolated situations. Real teaching is never isolated. But quite effectively administration is isolated. I sincerely believe that ALL administrators would be (for lack of a better term) better if they had to teach in the regular ed setting 1 year out of 5."

I agree with Teacher A; sometimes I can see the problem but I don't know how to fix it.  And that relates to Teacher B: I don't know how to fix it because I haven't done it myself.

To me the answer is that the principal is not the solution-giver or the expert, but the coach.  A basketball coach may never have successfully executed a jump hook but knows how it should be done and can call on others to model it.  And the coach can work with the player as he/she gets comfortable with the shot.

What are your issues with teacher evaluation, especially as a means of improving instruction?

Presentation at NAESP Convention, April 2011

I will present at the National Association for Elementary School Principals convention in Tampa.  The topic is "No Excuses:  Practical Steps Towards Changing Your School."

Here's the description:

How do you get started changing your school, especially if your staff isn’t thrilled about change? We will discuss how to build momentum for change and how to increase the odds that it will succeed. You can do it with the resources at hand. What changes might you have to make in your own attitude or approach to the job? What committees or structure can you put in place? What models can you use? And – what pitfalls should you look out for? The speaker, a veteran principal in a variety of schools, will encourage audience discussion and sharing.