Basildon Crown Court heard that 40-year-old Helen Carter shared sexually explicit messages and engaged in sexual activity with the schoolgirl in question.
The former English teacher, who began working at Bromfords School in Essex in 2012, admitted to kissing the victim and inciting her to carry out a sexual act over social media after the student approached her and came out as gay.
The student's family became suspicious and upon checking the girl's iPad found a number of incriminating exchanges.
Commenting on the case as a whole as well as Carter's conduct, Judge Jonathan Black said: "The victim described how you had become close, exchanging explicit sexual messages and texts. In my view your behaviour towards this child in your care constitutes a gross abuse of trust."
Whether the student had been groomed was unclear, with prosecutor Nneka Akudolu saying: "The Crown would assert this was a vulnerable individual but I'm not sure if I can say she was targeted."
Carter admitted to four counts of sexual activity with a child by a person in a position of trust, three counts of inciting a child to engage in sexual activity and one count of making indecent images of a child.
In addition to her prison sentence, Carter has also been placed on the sex offenders register and was made the subject of a sexual offence prevention order for 10 years.
