The Cape Breton Victoria Regional School Board says Memorial High in Sydney Mines will open, today.
Students were sent home early yesterday after someone set off a flare in the building.
Regional Police say the flare appears similar to the one found inside the North Sydney Wal-mart on Monday.
The store is still shutdown while a cleanup continues.
Police are asking anyone with information that can help identify the people responsible for lighting the flares to call their general number or Crime Stoppers.