New York City has embarked on an ambitious experiment, yet to be announced, in which some 2,500 teachers are being measured on how much their students improve on annual standardized tests.This is a bad idea, at least today and at least in New York City.
In theory evaluating teachers based on student performance is a good idea. But only if the schools are functioning properly in the first place. Imagine this.
Company A and Company B manufacture automobiles. Each company has several factories where cars are assembled.
Company A has perfected its assembly line such that 99% of the automobiles coming off the assembly line function properly and pass all the quality control tests. If the cars rolling off of factories A, B, and C are rolling off at a 99% pass rate, we have good reason to believe that all the workers, including the managers, are doing their job correctly based on the performance of the products. If factory D only has a 75% pass rate, there's good reason to believe that something has gone awry in this factory based on student performance. Furthermore, if the failing cars were tested and it was discovered that most of the failures were the result of the engine not functioning properly, then there's good reason to believe that the guy who assembles the engine isn't doing his job properly. The solution is for manager to can the employee.
Company B has perfected its assembly line. Only 25% of the automobiles coming off its assembly line do not function properly and fail one or more quality control tests. If the cars rolling off the assembly lines of factories A, B, and C are mostly defective, what do we know about the workers in these factories? Nothing. The assembly lines of Company B are defective and they could just as likely be the cause of the failure as the workers. Examining the products rolling off the assembly lines of Company B doesn't tell us much about the ability of the workers. The failures do tell us something about the ability of Company B though. Company B is the failure. The managers of Company B are responsible for the failure, not necessarily the workers. so who cans the managers? The market, assuming Company B was operating in a properly functioning market.
The public schools in NYC are company B operating under the delusion they are company A. That's how we get silly policies like measuring student performance to evaluate teachers. Using this same thinking, why doesn't NYC measure the performance of the schools to evaluate the performance of the management of the NYC school district, starting with the chancellor. You can bet this won't happen because the public schools are a political beast far removed from the free market. The only losers in this situation are the consumers, i.e., the parents and students.