QUEEN CREEK, Ariz. — The first day of school, a normally happy ritual, was fraught with conflict Monday at some schools opening in Arizona, echoing debates across the country over the risks of holding all in-person instruction amid the coronavirus pandemic.

In some districts, worried teachers resigned or called in sick. While Queen Creek Unified School District opened its doors, J.O. Combs Unified School District in neighboring Pinal County canceled its planned reopening Monday after an overwhelming number of staff said they planned to be absent.

The school board in the town of Queen Creek, about 40 miles (64 kilometers) southeast of Phoenix, voted last week to offer in-person instruction full-time. Jacob Frantz, a chemistry teacher at the high school and head of the local education association, resigned soon after the vote. Frantz said he knows of a dozen others who quit since the vote and said roughly 30 others have left since June, when the district first proposed doing all in-person instruction.

Stephanie Ingersoll, a spokeswoman for the district, said media reports have inaccurately reported the number of teachers resigning. She said “a small number” gave notice after the school board vote