Mark Robert Forbes didn't ask any questions the night of March 27, 2013, when his wife told him a girl they were babysitting had just alleged Forbes touched her inappropriately.

The former Albion Park Public School assistant principal has pleaded not guilty to five charges of indecently assaulting a child and one charge of aggravated sexual intercourse with a child aged under 10.

Charges were laid after two girls alleged Forbes touched them inappropriately during an overnight stay at his house. The younger girl also alleges the then 53-year-old performed sexual acts on her.

The girls' credibility was brought firmly into focus at Wollongong District Court Friday afternoon, as both sides made closing arguments.

Crown prosecutor Kate Ratcliffe called on the jury to consider the high level of detail the girls had provided when making their allegations, and their demeanours during recorded police interviews.

The older girl had "appeared to almost cringe as she described the accused putting his hand inside her shorts", as if she was "reliving the experience", Ms Ratcliffe said.

The younger girl similarly had "the demeanour of a girl who was telling the truth".

"You might have noticed she didn't speak for a long time," Ms Ratcliffe said.

"Instead, she put her hand to her forehead, down the sides of her face, gave a long sigh, then [made the allegations]."

But defence barrister Susan Oliver, acting for Forbes, argued the girls - though "adorable children" - were mistaken in their claims.

Ms Oliver told the jury the abuse was alleged to have occurred in rooms where the doors were open and the lights were on, in a compact house offering little privacy, when Forbes's wife could have walked in at any time.

Some of the abuse was alleged to have occurred when there were others in the room with Forbes and the girls.

"This would be a brazen act," Ms Oliver said.

She asked the jury to accept her client had been sitting with the two girls on a bedside railing and had touched the older one only to prevent her from falling, and not for any sinister reason.

But the Crown prosecutor questioned why Forbes hadn't made mention of the the non-sexual touching when asked by police the following morning whether he had touched either girl.

The jury heard Forbes also failed to mention any innocent physical contact to his wife when she confronted him on the night and again the following morning.

It was "extraordinary" that Forbes hadn't asked his wife on either occasion for further details of the girls's claims, Ms Ratcliffe said.

But Ms Oliver said Forbes's reaction was understandable given the "strained atmosphere that existed between the accused and his wife at the time".

Under cross examination, Forbes earlier told the court he was "slightly" drunk the night of March 27, having consumed a six-pack of beer.

He told the court he and his wife had earlier argued about the division of household chores.

Judge Mark Marien will sum up the case when the trial continues on Monday.