Thousands of dollars are being spent on special needs facilities at schools for children who sometimes do not end up attending.
A $180,000 fence is being put up around Hampden Street School in Nelson, initially because of a pupil who has a habit of running away, but now he is not at the school.
Similarly, Nelson College modified a toilet changing area for a student who enrolled but did not attend because his family had moved.
However, the Ministry of Education has no plans to introduce a policy requiring parents to give a commitment that their child will attend a particular school before there is a commitment to spend the money.
Ministry head of education infrastructure service Kim Shannon said it would be unreasonable and unfair to force children and families to commit to their attendance plans.
Nationally, the ministry has spent between $12 million and $17m a year on special needs modifications in the past three years.
In the Nelson region, the cost has risen from $674,842 three years ago to nearly $1m in the past year.
Hampden Street School principal Don MacLean plans to explain about the new fence to parents in a newsletter this week.
He said the pupil who was "a runner" had been at the school for most of the year, and the school had to keep a close eye on him. The boy had now gone overseas, and it was understood that he was not coming back to Nelson.
The boy's presence had triggered the ministry funding for the fence, but it was not built specifically for him, Mr MacLean said.
The school's board had discussed the matter, he said.
"We didn't want the school to look like a prison. The bottom line is the safety of our children."
The steel fence will be 2.2 metres high around the school field and 1.4m high along the rest of the boundary.
In a survey of parents, most of those who mentioned the fence were favourable, Mr MacLean said.
"This is one of those things that is positive for the children. It's going to make the children safer."
Nelson College deputy headmaster Tim Tucker said the school had an obligation to meet the needs of students, and sometimes this came with extra costs. "Our philosophy is to meet the needs of all students."
Two years ago, a student had enrolled and a toilet changing room was modified to meet his needs, Mr Tucker said. However, his family moved to the North Island.
Ms Shannon said the ministry had not considered introducing any procedures that would bind parents to a commitment for their child to attend a particular school, because a family's or a child's circumstances could change, for a variety of reasons.
The ministry's approach was to provide an inclusive education system, she said. This meant ensuring school buildings and grounds were ready for all children, whatever their needs.
School infrastructure should support improving the educational outcomes of children with special needs, she said.
Schools were funded for projected needs where possible.
Modifications made for one child, which generally meant changes to ramps, door widths and lifts, equipped a school for future enrolments by children with special needs, she said.
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