KITCHENER -- Schools in 16 boards across Ontario will be closed today, as the union representing public high school teachers holds another one-day strike.

The Upper Grand District School Board and Wellington Catholic District School Board are both scheduled to be part of the job action, while the Waterloo Region District School Board is unaffected.

It is the fifth job action in the Ontario Secondary School Teachers' Federation's series of rotating strikes during a contentious round of bargaining with the province.

The union, which represents 60,000 teachers and education workers, began one-day walkouts on Dec. 4 with a job action that closed schools across the province.

It has followed up with weekly rotating strikes that have closed all secondary schools and some elementary schools at the affected boards. In addition to representing high school teachers, the OSSTF represents education workers at some elementary schools.

Teachers were angered when the government announced that average high school class sizes would increase and four e-learning courses would be mandatory for graduation. The government has since scaled back those proposals, but OSSTF president Harvey Bischof has said it's not enough.

Education Minister Stephen Lecce has repeatedly said the key sticking point is compensation, with the union demanding a roughly two-per-cent wage increase and the government offering one percent.