Primary schools in some areas of the country say a relief teacher shortage is worsening, putting staff under pressure as the winter chill hits.
Porirua East School teacher Andrew Morris says the school's relief pool has dropped to one reliever, and most of the time children are divvied up among other classes when their teacher is sick.
"It impacts on all the staff at the school, the main impact of course being on the children and their education," he said.
He said he believed other previous relievers in the area had taken up full time positions.
Mr Morris said he has worked while sick.
"There's a lot of pressure to come in and get the job done.
"You tell the children, I mean, 'If you're sick, don't come into school.' But when it's yourself you want to come in and make sure you're doing the best thing for your kids."
In the last six years to 2017, the number of primary school relievers has dropped by almost 2000 to 6132, according to data from the Ministry of Education.
"New teachers previously tended to start in relieving roles but over recent years an increasing proportion start their teaching career in fixed term or permanent roles," a spokeswoman said in a statement.
'It's a crisis' - Auckland Primary Principals' Association
It's also increasingly difficult to find a relief teacher in Auckland, with extraordinary role growth, according to Helen Varney, President of the Auckland Primary Principals' Association.
"Teachers being away and trying to get relievers into your schools is a crisis.
"At the moment, schools are having to split classes, they're having to put several classes in with one teacher. And in one case I know there's been a school with five classes in the hall and the principal and a teacher looking after them for a day," she said.
Ms Varney said while traditionally teachers would take one day off when sick, they're now away for longer periods.
"That's the demands on them from the stressful jobs that they have with all the extra issues that are being put onto teachers that would normally have been in the past home and family."
Ms Varney says schools are calling for a relievers pool that knows their schools, communities and children.
She said the shortage of relievers is impacting students' learning.
"It impacts on their ability to settle quickly, engage with their learning, build a relationship and then continue to be happy while they're learning," she said.
The New Zealand Educational Institute President Lynda Stuart said a lack of relief staff is a symptom of a wider teacher shortage.
Ms Stuart said improving the relief situation would come from fixing the shortage.
Government investigating getting sick leave data
Education Minister Chris Hipkins said the Government's big challenge was recruiting new teachers.
He said there were variable reports from around the country on the relief shortage and it's something he's asked the Ministry of Education to review through the creation of a workforce strategy.
"How we can get actually get better data about this because at the moment we're kind of flying blind a little bit," he said.
Mr Hipkins said schools having difficulty sourcing relievers was "not okay" and that the Government does want to see fully-staffed classrooms.
He said the relief pool may increase as a result of an ageing teaching workforce, if teachers nearing retirement age don't want to work full-time but are happy to relieve.
Porirua East teacher Andrew Morris said professional development for relievers is missing and getting back into the workforce is difficult.
"In the past it was an option for people to think, 'Well I might leave full-time teaching and become a reliever' and these days I think if you're leaving teaching, you're leaving teaching because of the workload, because of all the other things that are going on," he said.
APPA President Helen Varney said teachers are considering retirement earlier due to the increasing demands of the role.
"Instead of saying, 'Oh, I'll give them a couple more years, you're saying, 'Why would I?'"
The Ministry for Education said in a statement it's investigating whether it would be feasible to collect sick leave information, through the anonymous and confidential leave data it collects as part of the payroll process.