A former Illawarra school teacher on trial for child sex offences interfered with two young girls while his own children were in the same room, a jury has heard.
The man's trial began Monday in Wollongong District Court, where he formally pleaded not guilty to five charges of indecently assaulting a child and a charge of aggravated sexual intercourse with a child aged under 10.
The 53-year-old stands accused of molesting two girls who stayed overnight at his home on March 27, 2013.
In an opening submission, Crown prosector Kate Ratcliffe told the court the man was drinking and reading in his study when the girls arrived at the home, and did not join them, his wife and two primary school-aged sons for dinner.
The assaults are alleged to have begun later in the night, when all four children were in the boys' bedroom.
According to the Crown case, the man sat on one of the beds, with the girls on his either side and one of his sons on his knee.
The group formed an audience for the man's other son, who was playing the violin with his back to them.
The older girl later told police the man touched and rubbed her inappropriately - including on her chest and genitals - during the boy's performance.
She said she looked at the man and didn't reply when he asked her: "Are you feeling uncomfortable?", causing him to remove his hand. "The accused kept telling [his son] to keep playing [the violin]," Ms Ratcliffe said.
The Crown alleges the man reached to his other side, inside the underpants of the younger girl and asked her "does that feel nice?", withdrawing his hand when she replied: "no".
The younger girl alleges the man twice took her hand and placed it inside his underpants during a later encounter when the two were alone in the guest bedroom. She further alleges he asked her to lie on the bed, pulled the neck of her nightie down and licked her nipples and her genitals.
The older girl disclosed the alleged abuse to the man's wife later in the night, telling her "your husband sexually abused me".
The woman initially dismissed the touching as "accidental", but drove the girls home when the older one approached her a second time and told her: "[the younger girl] said [the man] licked her vagina".
The man, who cannot be named for legal reasons, held a senior position at an Illawarra school at the time of the alleged offending, but has since moved from the area.
The trial continues before Judge Mark Marien on Tuesday.