Elizabeth Marland, who was formerly employed at Moor Hey Mathematics and Computing Specialist College on Far Croft, Lostock Hall, near Preston, entered guilty pleas to three allegations during a hearing before Preston Crown Court.
The charges against the 42-year-old defendant are understood to date back to a two week period in May last year.
The youngster cannot be identified for legal reasons.
The Post is legally restricted from revealing further details about the case.
Marland, who gave her address as Hawkhurst Avenue in Fulwood, Preston, was due to be sentenced this week but her sentencing was adjourned by Judge Beverly Lunt.
She is now expected to find out her fate on December 21 at Preston Crown Court.
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