Neil Morrison is accused of carrying out the sexual assaults while he was working as a teacher and assistant principal on the NSW south coast before his retirement in 2016.
The 69-year-old has pleaded not guilty to two counts of sexual intercourse with a child under 10 under his authority and one count of aggravated sexual intercourse with a child aged between 10 and 14.
He faced Campbelltown District Court on Tuesday for the first day of his trial, nearly three years after he was arrested.
Morrison had been a Year 3 teacher in Minnamurra Public School when he asked a girl to take a pile of books to the class storeroom, crown prosecutor Tony McCarthy said in his opening address.
He said the complainant would give evidence that Morrison followed her inside and closed the door behind him, pushing her into a kneeling position and raping her while she cried.
The teacher then pushed her against a shelf and raped her again, according to the prosecutor.
A year later, Morrison allegedly took advantage of an overnight camp on school grounds to take the schoolgirl into a secluded room.
He shut the door and closed the curtains and told the 10-year-old girl to be quiet as he raped her again, causing her pain, Mr McCarthy said.
The schoolgirl did not tell anyone about the alleged sexual assaults for years, the court was told.
The trial is set to feature evidence from another former student of Morrison's who claims he regularly used to grope her while she was his Year 4 student.
Morrison has not been charged over those allegations, which will be relied on by the prosecution as evidence of his tendency to act in a sexual way to his students.
The former assistant principal has denied the allegations against him.
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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