The president of one of the largest teachers unions in the country announced Thursday that the union wants all schools to reopen for in-person schooling in the fall. “The United States will not be fully back, until we are fully back in school. And my union is all in,” Randi Weingarten, head of the American Federation of Teachers (AFT), said in an announcement. Unions like AFT have been a major obstacle to districts trying to return to in-person learning, claiming that the risk of teachers contracting COVID-19 was too high in many locales and attempting to force safety measures that critics say were unreasonable. But circumstances have recently changed, with an increasing number of school employees receiving a COVID-19 vaccine, Weingarten said. Union data shows nearly nine out of 10 members have been vaccinated or have expressed a desire to get a shot. “We can and we must reopen schools in …