Nova Scotia's education minister has shot back at a union request to waive a section of the current collective agreement so long-term substitute teachers won't lose benefits due to Friday's one-day walkout.

"The chaos and uncertainty your planned strike action is creating for teachers is distressing," Karen Casey wrote in a letter to Nova Scotia Teachers Union president Liette Doucet.

"You have an opportunity to prevent this by reconsidering your decision to strike."

In a memo distributed Wednesday, the union told its members the walkout constitutes an interruption in service, which means long-term substitute teachers accumulating time toward benefits will be set back to Day 1. In the union's terms, they will lose their "consecutiveness."

Long-term substitutes are teachers who cover short-term leaves of absence.

It also said term teachers will not be paid or be able to accrue time for that day. However, unlike substitutes, they will get strike pay for the walkout.

Term teachers are hired for a number of reasons, including as a replacement for teachers who are absent from the classroom for a minimum of 175 days.

The union had said it would ask the province to consider not counting the strike as an interruption in service.

On Thursday, Casey replied in a letter that said she and her colleagues had received "numerous inquiries from teachers" worried about their status as a result of the strike.