Universities are generally employing familiar measures to fight the coronavirus: distancing, testing, tracing, and isolating. But the rollout of these policies — and their success in fighting outbreaks — varies widely from school to school. At some schools, all students must get tested at least once a week if they want to remain on campus. At others, even students with Covid-19 symptoms have difficulty getting tested at all. Some schools are providing single-occupancy rooms for students who should quarantine after being exposed to the virus, while others send students back to their dorms to wait to see if they get sick.