In rural Alaska, the federally funded Head Start preschool program has helped parents earn college degrees. It has put parents with drug addictions on paths toward recovery and educated children who have ended up in foster care. And, of course, it has readied youngsters for kindergarten. So it was crushing when one of Alaska's Head Start providers closed two of its preschools. The program suffers nationally from a teacher shortage — its teachers must have college degrees, and they can often earn more working in retail or at local school districts. The preschool closures in Alaska preview what other regions across the country could soon face.