Bernadette Smith, 35, had quit her job as a history and English teacher at Bannockburn High School on Friday after allegations arose that she had sexual contact with a 16-year-old student.
The married mother-of -three met head teacher Tom Black at the school on Friday before resigning her post.
However it emerged yesterday that she has now retracted that decision after speaking to her union.
Mrs Smith was held by police last weekend over the claims, part of which allege her and the pupil engaging in activity in a public park. She appeared in court on Monday morning to deny the charges against her.
She then met with representatives from the Educational Institute of Scotland, who advised her not to make her resignation official in writing - meaning she is still a member of staff at the high school. A spokeswoman from Stirling Council said: "The EIS have been in touch with the school to advise them that Bernadette Smith has retracted her resignation, which has implications for ongoing processes within the council. There are investigative processes we have to go through."