(AP) — With schools shut down for the coronavirus outbreak, districts and educators are launching a massive, unplanned test of virtual teaching. Virtual school — sometimes known by “distance learning” or other terms — has existed for decades. But it’s far from ubiquitous in U.S. schools because of digital inequities among students, concerns about implications for teachers, and other factors. Online education begins Monday in New York City, the nation’s biggest district. Teachers there have been coming up with digital versions of everything from high-school English discussions to kindergarten gym classes.