I see that this thread has been busy overnight. I'll quote here first another kind reply I received, and then respond both to it and to your reply.

If you give the parents the ability to "shop", what happens when everyone thinks that teacher X is the best English teacher for 7th grade and they ALL want their kids in her class?

For me, this is not a theoretical question, because I live in a state of the United States where there is actual "power to shop." In the entire state of Minnesota in the United States, there is public school open enrollment,

http://education.state.mn.us/MDE/StuSuc/EnrollChoice/index.h...

and the school district for the neighborhood in which I live includes open-enrolled students from the territories of more than forty other Minnesota school districts, with funding following the students on a per-capita basis.

http://www.house.leg.state.mn.us/hrd/pubs/mnschfin.pdf

Aspects of the system in Minnesota that are rigid and suboptimal as they are in many other states include

lock-step union seniority pay and promotion systems for nearly all public school teachers,

http://minnesota.cbslocal.com/2012/05/03/seniority-still-rul...

but parents with power to shop and funding that follows students allows school districts with the better programs, overall, to thrive and produce innovative new programs (e.g., language immersion programs, specialized fine arts programs, and school-within-a-school programs for highly gifted learners) and the schools that are forced to lay off teachers (alas, by seniority rather than by effectiveness) are the schools with laggard overall programs.

the evil socialist Canadian public school system

This is from your comment. I'm not aware what province you grew up in, but it's my understanding that there have been elements of school choice in some Canadian provinces in our liftime,

http://www.heritage.org/research/reports/2010/11/school-choi...

http://www.societyforqualityeducation.org/parents/canada-cho...

although just what is going on in Canada in comparison to other countries receives different degrees of emphasis even in Canadian sources

http://educhatter.wordpress.com/2012/02/19/school-choice-and...

and perhaps right now when Canada is in the world news

http://www.startribune.com/world/151854375.html

we might conclude that there are some difficulties with the system in some Canadian provinces.

Anyway, Canada provides an example, through its system of provincially administered health insurance programs,

http://www.hc-sc.gc.ca/hcs-sss/medi-assur/index-eng.php

of a general public subsidy program that still allows much user choice. Patients get to choose their doctors in Canada.

http://www.cwhn.ca/node/40789

In principle, as already observed in reality, it is perfectly possible for there to be a general public subsidy for some service that is deemed to have a positive externality, while still allowing user choice of the provider of the service.

There are other international examples of school choice. I particularly like the example of the Netherlands with its very wide array of choices for parents, all at equal publicly subsidized expense,

http://www.denhaag.nl/en/residents/to/Want-to-send-your-chil...

which has been studied for years as part of broader studies of parental choice in schooling.

http://www.eric.ed.gov/ERICWebPortal/search/detailmini.jsp?_...

http://books.google.com/books/about/Choice_of_schools_in_six...

By the OECD testing program called PISA, the Netherlands does as well as or outperforms other countries both as to helping students from disadvantaged families

http://www.oecd.org/dataoecd/5/5/49603617.pdf

and as to getting educational achievement results per unit of money spent by the school system.

http://www.pisa.oecd.org/dataoecd/50/9/49685503.pdf

I'm not opposed in principle to the idea of statistically ranking teachers and giving the power of choice to parents, but you guys have royally fucked it up in practice.

I'll heartily agree with you and with other comments here that the current state testing systems, which vary state by state, but which are mostly poorly designed, are a weak basis for publishing ratings of schoolteachers, but as you correctly point out, that's not to prove that a better system of assessing students and their academic progress has NO value in helping parents shop for schools. What I don't want to go back to is the day in which no one had any idea how well any teacher was teaching, because no one was looking, and no one was looking because parents couldn't shop for schools anyhow. If parents can make global evaluations of what is good for each of their children, better incentives exist to improve teaching, improve school administration, and improve all other aspects of the school experience.

Returning to the other comment's thoughtful question,

If you give the parents the ability to "shop", what happens when everyone thinks that teacher X is the best English teacher for 7th grade and they ALL want their kids in her class?

that is precisely the kind of situation that builds curiosity among other teachers about "What is that teacher doing that I'm not doing?" and among administrators about, "What value do families perceive in that class that they don't perceive in our classes?"

As other comments have already pointed out, parents in all countries of the world shop for schools at least by how they choose their residence addresses. But decoupling school choices from residence choices allows schools and families to respond more efficiently to their own mix of trade-offs. When many shoppers prefer one grocery store to another, and take their business to the better grocery store, what usually happens is that the worse grocery store changes the way it does business and improves its overall customer value proposition for shoppers. As I noted above, one HUGE problem with schools all over the United States, even schools in states that do not formally have "union shops" with mandatory schoolteacher union membership, is that administrators have little flexibility in reassigning teachers to the work that they do the best. So today is a somewhat slow process at the margins for schools to improve (by realigning staff assignments) as families shop for the best classrooms. But I've seen what Minnesota school districts have been able to do even within the limitations of the current system, and I'm confident that adding incentive for school improvement by giving learners more power to shop makes as much sense (as a matter of basic public policy) as it does for providing most other services.

AFTER EDIT: Commentary on the link submitted here by a blogger based in New York City,

http://nycrubberroomreporter.blogspot.com/2012/05/carolyn-ab...

which I learned about from a Facebook friend who lives in New York State and has been following the controversy on school testing in New York State closely.