A FORMER teacher who sexually abused students at Knox Grammar School will spend up to 4½⁄ years behind bars, with the judge who jailed him warning that ”no child is to be viewed by a teacher as a sexual opportunity”.Sentencing Craig Treloar yesterday, District Court judge Colin Charteris said his criminal activity had tarnished the reputation of the exclusive Wahroonga school.”He took advantage of children,” the judge said. ”He was their teacher. He had a position of trust. He abused that trust for his own sexual gratification.”Treloar, 50, has been in protective custody since his arrest in February last year. He shook uncontrollably as he was given a minimum two-year term.Treloar told the court he ”didn’t know anything else, other than how to be a teacher”. As a convicted child sex offender, he will be banned from working with children.His world revolved around Knox, where he was a student and, later, a highly regarded teacher, sports coach and boarding master. For more than 20 years he knew his crimes would come to light. He was arrested after two of his victims contacted police early last year.Treloar confessed to police but felt ”no sense of relief, because what I’ve done cannot be repaired”. He admitted offences, including indecent assault, against four students aged 11 to 13. They took place between 1984 and 1987 in his dorm room, while he showed the boys pornographic videos.Court documents reveal Treloar had indecent dealings with at least one other student who, the Herald understands, did not wish to pursue a complaint. Treloar was not charged over those matters.The court heard Treloar admitted showing students pornographic videos when confronted in late 1987 by the then headmaster, Ian Paterson. He was suspended from teaching for six months.Judge Charteris was not critical of Dr Paterson, saying Treloar did not reveal the extent of his inappropriate behaviour, such as engaging in sexual activity with students and showing films depicting bestiality and homosexual sex with underage boys.He accepted Treloar committed no offences after 1987 and was genuinely remorseful.Treloar was the first of five teachers charged over the alleged sexual abuse of former Knox students. Three have pleaded guilty, while two remain before the courts.In court, two of Treloar’s victims detailed the shadow of the abuse. As a 12-year-old, one fell asleep praying he would not wake up and vomited every morning before school.Judge Charteris said it was apparent the abuse had long-lasting effects and admired the victims’ courage in exposing it.One father told the Herald his son would phone home, insisting: ”I just want to die.” No sentence could give his son back ”24 years of an absolutely hellish life”, the man said.