School is out, but Ontario high school teachers are still ready to launch a job action next week that could affect some students before September.

Teachers with the Ontario Secondary School Teachers' Federation (OSSTF) will be in a legal strike position as of Monday, when the organization says teachers will stop doing all extra-curricular activities, spokeswoman Lori Foote confirmed.

That move will affect any school with an early start date to the school year or schools that start athletic programs in August.

OSSTF teachers in Durham and Peel Regions launched a weeks-long strike at the end of the last school year before they were forced back to work by a ruling from the Ontario Labour Relations Board, as well as back-to-work legislation passed by the provincial government.

Tension has remained high between teachers, their school boards and the province in the months since, and many expect some labour disruption when students return to class.

School boards, meanwhile, are warning it's not just high school students who could stop working in protest.

Michael Barrett, president of the school boards' association, said with no contract talks scheduled between the province and its 115,000 teachers, "there will be some kind of job action come Sept. 8."