Ben Hasty/MediaNews Group/Reading Eagle via Getty Images What do we need to open schools safely? It’s a question on millions of Americans’ minds as the Covid-19 pandemic lurches into its 11th month, with many children still learning at home, many parents beyond burned out, and some of them forced to quit their jobs to take care of kids. It’s also a question with seemingly limitless answers, as states, school districts, and teachers unions have been left to negotiate safety among themselves — with, until recently, little guidance from the federal government. In Arizona, for example, many school districts are open for in-person instruction, even as the state posts one of the highest test positivity rates in the country, at close to 15 percent. In Fairfax County, Virginia, meanwhile, some parents were outraged after a teachers union implied in a now-deleted tweet that schools shouldn’t reopen until students are vaccinated — which probably won’t be until 2022. (The union now says the tweet referenced a “best-case scenario,” not a demand.)