The man, who has not been named to protect the identity of his victims, faced the County Court of Victoria on Tuesday over the offending against his former students in 1983.
The offending left the victims with lifelong impacts, which Chief Judge Amanda Chambers described as brazen and a breach of trust.
"Your offending was a breathtaking breach of the trust that (a victim) was entitled to as a student under your care, supervision or authority," Judge Chambers said.
A jury found him guilty of five offences in December, including sexual penetration of a child aged under 16, for offending while teaching at Traralgon High School in Gippsland.
He was convicted of four counts of indecent assault against the girl, who was in year 11 at the time.
In 1983, he touched her inappropriately, including by using a skin-fold test to measure private parts of her body.
Another instance involved the man assaulting the victim on school grounds over the summer holiday period, which Judge Chambers said was "predatory and reprehensible".
"(The victim) says she came an isolated teenager due to the hurt, confusion and pain she experienced after your offending," she said on Tuesday.
The man continued working at various schools after leaving Traralgon in 1983, moving to Presentation College in nearby Moe and then St Anne's Gippsland in 1989.
He moved to NSW in the 1990s, where he had four children, one of whom he subjected to 14 years of "depraved and sadistic" abuse, a judge found in 2016.
From age five to 19 the girl experienced sustained sexual abuse and torture, often while she was detained in a dilapidated tin shed which used to be a chicken coop.
Now aged 69, he is serving one of the longest Australian sentences for child abuse over that offending - 46 years - and will be eligible for parole when he is 96.
Judge Chambers said the man's offending had only increased over time.
"Your offending reveals a pattern of persistent sexual deviance," she said.
Appearing via video link from Barwon Prison, the man wore a long white T-shirt and shorts, and at times shook his head and crossed his arms.
Judge Chambers said he had shown no remorse and had categorically denied the offending.
The former teacher was sentenced as a serious sexual offender and handed a total jail term of seven years and six months.
Judge Chambers noted he is serving more than 40 years for crimes in NSW, with it being more than likely he will die in custody before being released.
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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