Why are schools in America in a a decade-long “learning recession” ?

Almost everywhere in America, students are performing worse than their peers were 10 years ago, according to new, district-level test score data released Wednesday by the Educational Opportunity Project at Stanford.

Compared with a decade earlier, reading scores were down last year in 83 percent of school districts where data was available. Math scores were down in 70 percent. The declines have affected both rich and poor districts, and crossed racial and geographic divides.

By Claire Cain MillerFrancesca Paris and Sarah Mervosh