LONDON, ONT. -- The Thames Valley District School Board is warning parents that if secondary teachers conduct the threatened walkout next Wednesday, the board will close all secondary schools.

The board statement says there is no option because without teachers on duty there is no way to ensure student safety.

Out-of-school activities, including field trips and sporting events, will also be cancelled for the day.

Parents are encouraged to prepare alternate attangements for their children as a precaution.

All schools to close in Huron and Perth

The Avon Maitland District School Board says all schools, including elementary schools in the region, will close if there is a walkout.

That is because the walkout would include office staff, educational assistans and other support staff at both elementary and secondary schools.

That staff handles student arrivals, and the board says, "there would not be sufficient supervision to ensure their safety."

Adult credit programs will be cancelled, but child care and Early ON programs will stay open.

- With files from CTV London's Matt Thompson