A mother said her 8-year-old daughter at Selwyn School, a decile 2 school of 450 students in Rotorua's Western Heights, was allowed to search for "black bottoms" and watched a superhero movie with an R13 rating for violence, horror and cruelty.
"Another student had gone on the Chromebook she's been issued and went on a site that had naked people on it," the mother said.
"They are allowed to watch whatever they want during class time."
Another mother said her 7-year-old son had been acting "weirdly" after watching inappropriate content on YouTube at the school.
"He will come home throwing his bum around, talking about 'butt'. It's just like wow!" the mother said.
"He came home and said, 'I watched a man killing a lady, he was smashing her on the head.'"
School principal Peter Barker declined to comment.
"We have policies and procedures in place for parents to raise issues through the appropriate channels," he said.
But the mother said she complained to Barker about it last week and nothing had changed.
"He said he had spoken with the students and yes, they do look at stuff they shouldn't be looking at, but the teacher is looking over their shoulder," the mother said.
"He said he was going to roll out a programme to prevent that from happening, but the students are still able to access really disgusting material."
Ministry of Education deputy secretary Katrina Casey said no one had complained to the ministry about the issue.
"We have contacted the principal and he has confirmed that the school has policy and procedures regarding the appropriate use of internet enabled devices and that it has received a complaint," she said.
"When a complaint is received by a school it will follow its complaints policy and the school is working its way through this at present.
"It is important that the board of trustees is permitted to manage this process, and is able to seek advice and guidance from the NZ School Trustees Association if required.
"We are not conducting an investigation and we will provide support and advice to the school if required."
Netsafe director Martin Cocker said the Government-funded Network for Learning (N4L) provided all schools with a web filtering dashboard enabling each school to limit what children could access through the school's network.
But he said that was not a "fail-safe" system because the internet was constantly changing and because some students could access the internet on their own devices without using the school network.
He said the Ministry of Education also funded Netsafe to take calls from any parents concerned about school internet issues.
"Parents can call Netsafe and Netsafe will talk to the school about what its policies are," he said.
"We have no enforcement powers, but we certainly can help them to fix any safety-related problems they may be facing."
• Netsafe's tollfree line is 0508 NETSAFE (0508 638 723).