Lauren Coyle-Mitchell, 36, was sentenced after performing a sex act with a girl of 15.
The affair happened when Coyle-Mitchell and the unnamed student were at Lena Edwards Academic Charter School in the US state of New Jersey.
Prosecutors at Bergen County Superior Court said the sexual assault happened at the married teacher’s home in Lyndhurst in 2015.
Other teachers noticed there were “inappropriate” interactions between the pair on a class trip, US media reported.
Investigators believe there was “at least one” encounter at Coyle-Mitchell’s home.
At the time, she tried to clear her name with a Facebook post, where she defiantly wrote: “Tragic accusations have been brought up against me.
“They are not true and my name will be cleared.”
At her plea hearing, the disgraced former teacher admitted performing a sex act on the girl and said their affair began with explicit texts.
Her firefighter husband looked on in the courtroom as Coyle-Mitchell was sentenced.
“Do you acknowledge that these acts were emotionally and morally damaging to this woman?” her attorney John Latoracca asked.
“Yes,” she replied.
She was arrested at the time, before being arrested again in 2016 after prosecutors said she violated a court order by contacting the victim.
In January this year, she pleaded guilty to second-degree aggravated sexual assault.
She had originally been charged with a first-degree aggravated sexual assault and second-degree official misconduct and child endangerment.
The state Board of Examiners removed her teaching qualifications – including for teaching disabled students – in April.
She must serve 85% of her sentence before she is eligible for parole with lifetime suspension under the No Early Release Act.
Coyle-Mitchell must also register as a Megan’s Law offender, and is banned from ever again holding a teaching or government job.