Is a value-added method the middle ground?

While teachers have largely criticized an effort to evaluate them based solely on student test scores, a columnist writes that a value-added approach is a possible compromise. Value-added education -- supported by Education Secretary Arne Duncan -- compares a student's achievement from one year to the next. However, teachers unions have been critical of the value-added approach, saying that standardized tests do not measure student achievement or progress. The Porterville Recorder (Calif.)