Michelle Lynn Dennis, 33, is facing jail over child sex offences committed in 2007 against two students, aged 14 and 17.

The County Court in Ballarat was told during a plea hearing that Dennis was teaching at Ballarat High School when she started sending sexual text messages to one of the boys in 2005. By the time of her arrest in October 2008, she had sent more than 1000 messages, some containing naked photographs of herself, to the boy, and more than 300 to the other boy.

A friend of one of the victims also received a text message from Dennis suggesting a threesome.

The court was told the music teacher had sex with one of the boys twice, and oral sex with the other boy, who was no longer at school.

Crown prosecutor Brendan Kissane said Dennis collected one of the victims from near his home one night and drove him to a park where they had sex. Afterwards, she continued texting him telling him how good it was.

He said that at another time, Dennis offered to drive him home, but instead took him to her house for sex.

The court was told Dennis drove the other boy to her house, where she gave him alcohol before engaging in oral sex. Both boys told their friends about the sexual liaisons.

One boy said in his victim impact statement that the incidents caused him to perform badly in exams and he lost a scholarship he had earned. He said he felt dirty, embarrassed and ashamed.

Defence barrister Neill Hutton said his client had been the victim of a series of violent relationships and suffered a miscarriage in the year of the offences.

He said Dennis was drinking up to two litres of wine a day.

Mr Hutton asked the court for leniency, saying his client had already been severely punished by losing her job.

But Mr Kissane said the court had no other option than to impose an immediate jail term.

Dennis was remanded in custody until Friday, when she is expected to be sentenced.