Last school year, about 100,000 Oregon students missed at least 3-and-a-half weeks of school, an investigation by The Oregonian has found. Missing that much school — 10 percent of school days, enough to be tagged "chronically absent" — puts children on track to fall behind their peers for years. Some will never earn a diploma. And while no state has worse attendance statistics, few Oregon schools have raised alarms. The Oregonian gained unprecedented access to student-level data on every public school in the state for a five-part series on absenteeism and its disastrous effects.