An 11-year-old autistic boy was discovered crying out "I'll be good, I'll be good" from the locked room at the school during lunchtime.
Education Minister Hekia Parata immediately moved to outlaw the practice.
The Herald then applied to find out how many other complaints had been made about seclusion rooms in the past five years.
The ministry deemed that to be a substantial undertaking that would "unreasonably burden the ministry" but agreed to look as far back as 2014.
During that time the Ministry said there were four substantive complaints and investigations: at Miramar Central School; Ruru Specialist School; the Amber Centre; Sara Cohen school.
Then this afternoon, the Ministry said it had received a complaint about one more school in October 2012.
Further investigations detailed
In its OIA response, the Ministry said the details of the Miramar complaint were already public, and an action plan was in place.
Ruru school, in Invercargill, disputed it was using seclusion but has now removed the door to the room. It is now a quiet space with soft furnishings. The Ombudsman is investigating.
It also sparked a working party on seclusion and restraint, which led to new guidelines released last month.
The Amber Centre, in Hamilton, was investigated in September 2014. The ministry said it received a complaint about the actions of a staff member at the centre, of which one part referred to locking children in a room. Amber was a small unit where six to seven children at a time with severe behavioural problems were sent from other schools, it said.
The centre was temporarily shut while an investigation was completed. The police did not lay charges. A government employment lawyer also found there was not enough evidence to proceed, but the staff member resigned last November.
Given the students had by that stage been enrolled elsewhere and "centres such as Amber were not consistent with the direction in which Special Education was moving", the facility was closed.
The report on the centre was withheld due to privacy concerns.
A complaint about Dunedin's Sara Cohen School was made in February. A government manager was put in place and a staff member resigned. A second was suspended while the investigation was ongoing.
The report into Sara Cohen was also withheld, but the ministry said the allegations were "concerning" and included seclusion, but were disputed.
The ministry withheld the names of two other schools where there were complaints, but investigations were not completed. The ministry concluded the schools were using "calming rooms" appropriately, for example with staff watching and parental consent.
Read the report here (Story continues below)
"A small dark space"
Although the ministry was unwilling to dig further back than 2014, the Herald was able to get a report into Arahunga school after asking for it by name.
An 2013 investigation details a complaint from a family who said its child had been locked in a time-out room and became very distressed.
The family also saw other children, crying, locked in the room, described as "a small dark space", for a long time.
A piece of four-by-two wood propped against the door of the room kept it shut.
Investigators asked the school to review its policies and apologise to the family.
Read the report on Arahunga here (Story continues below)
This afternoon the Ministry revealed details of the 2012 complaint about Tawa Intermediate School, which was sparked after a parent raised concerns about his son being placed in a small room to manage his behaviour.
The Ministry discussed this incident with the school which explained that the space was a ''withdrawal room'' for students, and that the room was never locked when in use.
Following a visit to the school, the Ministry recommended the school transform the room into a more welcoming and friendly space for students' use, and that it be made clear that it is an ''individual learning space'' that students use on a voluntary basis.
Those changes were put in place by December that year, the Ministry said, and no formal investigation took place.
A ministry report this month revealed as of this year 17 schools used seclusion, but there was a risk of more as it was self-reported.
The ministry has now requested all schools cease using the rooms.
Green Party education spokeswoman Catherine Delahunty said the education select committee had heard this morning that 17 schools had self-reported using seclusion rooms.
The ministry told the committee it was supporting those schools.
"One of the issues we are concerned about is those schools have self-reported, so we're relying on what they have told the ministry," Delahunty said.
"It's good the ministry wants to help them, but it won't solve the fundamental issues."
She added: "I don't know what form that help will take, or whether there's other schools who haven't reported those [seclusion rooms] because they're unclear about the difference between a time-out room and a seclusion room."
The admission from the Government that more schools had come forward to say they were using seclusion rooms showed schools did not have enough support or resources to properly educate and look after special needs children, she said.
However, the concern now was that students will be excluded instead, she said, as schools struggle to cope with demanding behaviour.
"We have parents getting told to come and take their child away, so that's the risk, when we get rid of seclusion rooms parents are being rung up to take their child home."
Delahunty said: "All of this is a sign of a stressed system. There needs to be a complete system change around how these children are supported. We know there's no training for teacher aides, and no funding for teacher development.
"Taking away seclusion rooms isn't enough. There needs to be a national comprehensive plan to support all schools, not just the 17 that identified as using these rooms."
