For teachers, parents and most youngsters, it’s back-to-school time. But for 400,000 children, it’s an even more important occasion — starting school for the first time. Most of them are ready for school, and, years later, most of them and their parents will look back fondly on those first few weeks of school. Sadly, about one-third of the children who are starting school aren’t ready. Many of these youngsters still will be behind by the time they reach third grade. Many may never be able to catch up with what their schools — and our society — expect them to learn and be able to do. This is a problem — and there is a solution. Taking the long view from early childhood to young adulthood, there is increasing interest in creating a more “seamless” system of learning that begins early and assures that students can successfully finish school and move on to higher education or job training and, eventually, into the work force.