Last week, the province's labour board ruled schools must hold summer classes for students in Grades 10 to 12 who failed a course which cannot be retaken next year.
The board asked school districts to compile a list of these courses and show them to teachers by noon today.
But some B.C. municipalities have already announced closures.
Chilliwack, Williams Lake and Campbell River say they will cancel summer classes, but have not said if the board's ruling will force them to offer courses considered essential.
Prince George says it has no courses meeting the board's conditions and it will cancel all summer classes as a result.
Abbotsford says it will make courses the labour board deemed essential accessible through the district's online learning website.
More than 40,000 teachers started a provincewide strike on June 17 that has cancelled classes indefinitely for more than half a million students.