If you want to know why school reform initiatives tend to go nowhere, you could watch this week’s Shaftesbury Society presentation from John Redmond, you could hang out with Terry Stoops, or you could read a lengthy first-person report in the latest issue of The Atlantic. Former New York City schools chancellor Joel Klein fills eight magazine pages with a detailed description of education dysfunction. TO COMPREHEND THE depth of the problem, consider one episode that still shocks me. Starting in 2006, under federal law, the State of New York was required to test students in grades three through eight annually in math and English. The results of those tests would enable us, for the first time, to analyze year-to-year student progress and tie it to individual teacher performance—a metric known in the field as “teacher value-added.” In essence, you hold constant other factors—where the students start from the prior year, demographics, class size, teacher length of service, and so on—and, based on test results, seek to isolate the individual teacher’s contribution to a student’s progress. Some teachers, for example, move their class forward on average a quarter-year more than expected; others, a quarter-year less. Value-added isn’t a perfect metric, but it’s surely worth considering as part of an overall teacher evaluation. After we developed data from this metric, we decided to factor them into the granting of tenure, an award that is made after three years and that provides virtual lifetime job security. Under state law at the time, we were free to use these data. But after the New York City teachers union, the United Federation of Teachers, objected, I proposed that the City use value-added numbers only for the top and bottom 20 percent of teachers: the top 20 percent would get positive credit; the bottom would lose credit. And even then, principals would take value-added data into account only as part of a much larger, comprehensive tenure review. Even with these limitations, the UFT said “No way,” and headed to Albany to set up a legislative roadblock.