SYDNEY, June 29 - Three Year 4 classes participated in the day-long activity at St Justin's Catholic primary school in Oran Park, in southwest Sydney, on Tuesday.
Two classes were told early on that it was role play, but students in the third class were told they would be removed from their families at the end of the day because their parents weren't looking after them.
After a backlash from some parents, who say it's "emotional abuse", the Catholic Diocese of Wollongong will look at changing the way its executed, assistant to the director of schools Tim Gilmour said.
"We've run it previously and had really good outcomes and that wasn't the case this time," Gilmour said.
"We'll certainly be changing things and thoroughly review it."
It comes after Natalie Wykes, a mother at the school, said her son came home and told her he got "really scared" at school.
"This is emotional abuse," Wykes told Fairfax on Thursday.
"This should never happen to another child."
Gilmour insisted the diocese was taking the concerns seriously but defended the activity, saying it was related to a text the children were studying.
The activity aimed to provide children with a deeper understanding of the nation's history, but the execution and outcome were "not what anyone would want", he admitted.
"No teacher intends to go in and distress students," Gilmour said.
"The execution probably didn't match the intention and we accept that criticism."
Some parents did support the lesson, with Gilmour saying he heard reports it was a source of good dinner conversation.