Some Ontario school boards say classes could be cancelled with very little notice if they don't have enough teachers available due to high rates of COVID-19.
Classes are set to resume in-person on Monday after schools began the term with online learning.
In a message to parents, the Toronto District School Board -- the province's largest -- says it's taken numerous steps to ensure staffing levels are as high as possible, but last-minute class cancellations could happen.
The Rainbow District School Board in northern Ontario says it may have to cancel classes day-of if there aren't enough teachers.
And the Ottawa-Carleton District School Board says it will make "every effort" to keep classes and schools open, but if it cannot operate safely, a class or school may have to pivot to remote learning.
It says it will try to notify parents of any cancellations or closures the night before.