Scott Calvert & Douglas Belkin:

Teachers calling in sick from Covid-19 are prompting superintendents across the country to close schools and move classes online, forcing parents to scramble for child care and reorder work schedules.

Nationally, more than 4,500 schools will be closed at least one day this week due to the pandemic, the highest number this academic year, according to Burbio Inc., a Pelham, N.Y., data company that tracks K-12 school closures.

On Wednesday, Chicago Public Schools, the nation’s third-largest district, canceled classes after the teachers union said the classrooms presented unsafe conditions. City leaders called the vote by the Chicago Teachers Union an illegal job action and said teachers who didn’t report to work wouldn’t receive pay.

Districts in other cities such as Atlanta and Milwaukee moved over the weekend to shift classes online as the highly contagious Omicron variant has driven a surge in cases.