New Zealand teachers are finding people who do not attend their schools are joining virtual classes after video links are posted online, NZME understands.
The "Zoom bombing" phenomena in classrooms is being put down to high schoolers "pushing boundaries" during online learning in Auckland, where virtual lessons remain while the region is in alert level 3.
Zoom is a video-conferencing service whose popularity has exploded during the Covid pandemic as workers, students and teachers have stayed home.
Auckland Secondary School Principal Association president Steven Hargreaves was aware of the issue, which often happened after Zoom links appeared on social media platform Reddit.
He thought such behaviour was "entirely predictable".
"We're dealing with teenagers."
Hargreaves said: "The last thing you want is a lesson being sabotaged by some clown getting online with your class."
However, he said there were measures in place to help prevent incidents like this happening and schools needed to get ahead of it. "The simplest thing is probably to have a waiting room and that means that the teacher must admit each attendee on the Zoom call one at a time after they've identified who that student is."
Post Primary Teachers' Association president Melanie Webber was aware of students finding "creative ways ... to disrupt online classes" but she would not elaborate "for obvious reasons".
"Teenagers pushing boundaries is something that has been happening since time immemorial," she said. "Teachers are great at creating safe and respectful learning spaces at school and are now trying to do the same in online learning situations."
The Ministry of Education and Netsafe have provided advice to schools since last March.
The ministry's deputy director of sector enablement and support, Katrina Casey, said there was advice specifically on "Zoom security and setup to prevent 'Zoom bombing'".
Netsafe chief executive Martin Cocker said similar things happened a lot during the first lockdown last year and it was disappointing to know it was ongoing. "It's up to schools and educators to make sure that they are ahead of those risks and they've got plans in place to deal with them."
Cocker said people given access to a network could cause disruptions "and that includes students who are trying to unravel teachers".
Zoom said it was "deeply upset" on hearing of the incidents and "strongly condemns such behaviour".
A company spokesperson said "meeting passwords" had also been enabled alongside the waiting rooms, with other protections for teachers too.
Reddit has been contacted for comment.