Inside Hoboken’s combined junior-senior high school is a storage closet. Behind the locked door, some mothballed laptop computers are strewn among brown cardboard boxes. Others are stacked one atop another. Dozens more are stored on mobile computer carts, many of them on their last legs. That’s all that remains from a failed experiment to assign every student a laptop at Hoboken Junior Senior High School. It began five years ago with an unexpected windfall of stimulus money from Washington, D.C., and good intentions to help the district’s students, the majority of whom are under or near the poverty line, keep...