Neil Albert Futcher, 69, is accused of sexually abusing six boys as young as 11 between 1974 and the early 1980s when he was a teacher at Trinity, and later in his role as a swimming coach.
He has pleaded not guilty to all 22 offences, including eight counts of buggery and 12 counts of indecent assault on a male.
In his opening address, crown prosecutor Giles Tabuteau told the District Court jury Futcher organised holiday trips during which he allegedly fondled and raped boys, and that incidents of abuse also allegedly occurred at his Drummoyne apartment.
"There's a tendency of the accused to have an interest in pre-teen boys ... and to act out that particular sexual interest," he said.
Mr Tabuteau said that one victim met with the accused in 2015 and Futcher allegedly said to victim: "I'm asking you to be forgetful ... I'm not asking, I'm begging."
Futcher allegedly asked the victim to say nothing about the abuse if the police questioned him, Mr Tabuteau told the court.
Description of acts are too explicit to be published, but it was alleged victims were often shown porn before being assaulted.
Futcher's defence attorney, John Galluzzo, said the alleged incidents occurred 42 years ago and the "when and where" would be challenged in the trial.
"These are matters that we will be saying did not occur," Mr Galluzzo said.
The trial is expected to last five to six weeks.