When schools are disrupted, it’s often because teachers, staff and other adult employees have gotten sick. By some estimates, more than half of U.S. schools have been offering at least some in-person classes. Many of the district’s 150,000 students are from disadvantaged families, and about half attend at least some in-person classes. Detroit, which has roughly 50,000 students, said it will suspend in-person classes next week because of the city’s rising infection rate. The trend will need to reverse for schools to start offering in-person education in January, as hoped, Lawson said.