A teacher named Liu in Henan province died at home on October 28, shortly after giving an online lesson to students. The cause of death was listed as a stroke.

His daughter suspects the real cause. She collected recorded video showing a gang of thugs hacking into her mother’s latest lesson, talking loudly, playing music and hurling slurs.

A statement from local authorities issued on November 2 said the allegations of an online disruption were being investigated, but ruled out any criminal offences.

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The teacher’s death has raised public awareness of a type of cyberbullying known in Chinese as wangke baopoor literally “online class bombing”.

This is relatively new in the field of education. In the traditional brick-and-mortar school, strict discipline makes such disruptions less likely, and there are often security guards to back it up.

But the online domain is different. By hacking or with the complicity of a misguided student, it is relatively easy for unruly gatecrashers to enter an online classroom.

In the case of Henan province, the teacher was giving a digital history lesson to first-year high school students via DingTalk, a platform developed by Alibaba, when the disruption happened. Liu’s husband said it was not the first time such an intrusion had happened.

In a statement, DingTalk said it was trying to gather more information about the case and was cooperating with a local investigation. The platform, originally designed as a business conferencing service, has expanded to online education during the COVID-19 shutdowns.

A young teacher named Xu in Shandong Province explained how an online class on DingTalk can go wrong.

If there are too many students, she says, a teacher can switch from “class” mode to “conference” mode.

“With class mode, you can press the mute button for all participants and easily kick out troublemakers,” Xu said. “It’s more difficult in conference mode.”

Some older teachers, long accustomed to the classroom discipline they took for granted, may be caught off guard and unsure how to deal with sudden outbreaks of pandemonium, Xu said.

Hackers can have a number of motivations. They could act for students who resent a teacher or classmates. Or disrupting a class may just be a malicious lark for them.

One of the most infamous online gatecrashers is a netizen who goes by the name of “Menglei” or Lachrymose Dreamer.

Technicians believe his online name may be an attempt to impersonate a well-known esports player. At the beginning of September, this player launched an appeal pleading for the end of the abusive interruptions of online lessons.

Students and teachers in Shanghai reported similar disruptions.

According to Shanghai News Radio, student Xiao Xia was attending an online class in September when she heard someone shouting, “Teacher, I want to go to the toilet!”

Police sirens ensued and the screen became a hodgepodge of chaotic activity.

“A young man let out a torrent of very insulting slurs,” Xiao Xia recalled. “Since our teacher failed to expel these intruders all at once, the only option left was to end the class prematurely.”

Wang Xiaofei, who teaches at a middle school in Shanghai, suffered two invasions during a meticulously prepared online course for 1,000 students. Afterwards, according to Shanghai News Radio, she felt guilty.

“Why did this only happen in my class?” she wondered, according to the report.

The torment made her wonder if she was really fit for her job.

According to The Paper, a Shanghai-based Chinese digital media outlet, a student from Liaoning province reported in September that an online nursing course had been invaded by swearing hackers. The didactic material was replaced on the screen by video games and pornographic images.

The greater the shock, the greater the satisfaction of the authors, it seems.

Shanghai News Radio said 16 culprits invaded a middle school Chinese class reveling in their exploits later in a chat room. One said: “Some teachers faced with this could act decisively to cut the mics, but not this one. She was stunned and left on the verge of tears.”

In a recent central government circular aimed at combating cyber-harassment, specific provisions define the responsibility of online platforms to protect the legitimate rights of Internet users.

Baidu, a major Chinese search engine, recently posted a notice stating that “recent monitoring has suggested that some users have posted notices about recruiting others into secretive groups specializing in organized invasions of online courses on Tencent Meeting or DingTalk.

The same notice revealed that 410 illegal posts were removed and 58 accounts were processed for serious offenses. The company also provides a channel for users to report irregularities.

In September, Tencent Meeting launched a feature that allows chat moderators to use a click of a button to block participants from speaking, sharing images or leaving comments.

In an interview with The Paper, Liu Xingliang, an expert with the Ministry of Industry and Information Technology, said schools should train teachers on how to remove attendees, blunt microphones or suspend an online class meeting.

Some legal experts have suggested that these online invasions should be classified as criminal offences.