Chicago canceled classes on Friday amid a standoff with the city’s teachers union (CTU), which is refusing to teach in-person. Parents were told late Thursday that classes were axed for the third straight day as “we continue working to get CTU staff back in our buildings.” A small number of schools may be able to offer in-person activities because some teachers were bucking the union and have been showing up at schools, Chicago Public Schools CEO Pedro Martinez said. Parents, though, should not send their children to school unless the principal there confirmed that it would be open on Friday. CTU members voted earlier this week to shift to virtual learning after a rise in COVID-19 cases in Chicago and among students and staffers. Members refused to return to the classroom unless the number of cases subsided or the city agreed to a list of demands, including forcing students to …