The Aranda Parents and Citizens Association wrote to the ACT government last year furious that the library and the community room could no longer be used for their intended purposes thanks to a sudden boost in enrolments.

The Education Directorate eventually responded by re-drawing Aranda's priority enrolment area, commissioning the demountable and reviewing the use of non-teaching spaces as classrooms. Findings of the review have not been made public.

Aranda Primary principal Phil Gray said while other principals in similarly popular schools had expressed their frustrations with space limitations, the boost in public school enrolments was also cause for celebration.

He said he was "thrilled" with the installation of the $1 million, air conditioned building, currently home to two year 3 classes.

"The proof's in the pudding that schools are providing for the needs of our families and particularly our young people," Mr Gray said.

Australian Bureau of Statistics data released last week showed enrolments at Canberra's government schools grew more than 17 per cent over the past five years, vastly outstripping growth in Catholic and independent schools.

The enrolment boost has led to some challenges, especially in Canberra's north. Four Gungahlin schools have also received demountable classrooms, a primary school will be built in the new suburb Taylor, and the Australian National University has been enlisted to help improve the directorate's modelling.

Education Minister Yvette Berry said: "You can project as far as you can but sometimes human behaviour can be a bit fickle, so you do as much planning as you can to take into account what you think's going to happen then you have to make adjustments along the way depending on the choices that families make."

Aranda Primary will keep its transportable as long as needed, Ms Berry said. The school has 555 students enrolled this year and, with the new classrooms, is running at 82 per cent capacity, according to the Education Directorate.

Former Education Minister Shane Rattenbury changed the definition of school capacity mid-2016 to include spaces traditionally quarantined for special education and non-mainstream classes in future projections.

The change, described by the ACT Council of Parents and Citizens Associations as "cynical", allowed for up to hundreds of new spots in schools without adding any new infrastructure.