Posters should be displayed in schools warning against violence or threats to staff, a teaching conference will hear.
A motion to the National Education Union (NEU) Cymru conference calls for posters to be put up in reception areas similar to those shown in GP surgeries.
The union claims aggressive behaviour is a growing concern, calling for a review of the causes.
The Welsh Government said councils and schools needed to ensure schools were a safe environment for all.
One teacher said he had been punched by a teenager when he tried to intervene in an incident on the yard.
As well as the physical impact and a suspected broken bone, he says he became stressed and anxious and did not return to work for a year, before formally leaving his job.
“There didn’t seem to be any consequences for the pupils or any support for me,” he said. “What was I feeling like?”
“Staff safety and well-being is just as important as pupil safety and well-being. It should be equal – it’s not equal”.
Another secondary school teacher said she had been forced to take time off work after several incidents including threats of violence and “a torrent of abuse” from pupils.
She felt drink and drug abuse was a factor, something schools were “not well equipped to deal with and are loathe to recognise”.
“These incidents are happening more and more frequently”, she said.
The union, which is debating the issue in Newport on Sunday, said that funding cuts are making the problem worse, as well as issues around discipline at home and wider problems in society.
David Evans, Wales secretary of NEU Cymru, said: “It’s not an every day occurrence in every school – incidents are few and far between, but even one attack is one too many.
“It highlights the difficulty in dealing with it. Managers have to deal with unusual incidents but they have to deal with it properly and ensure people are protected in their workplace.”
At the lowest level there was verbal abuse, then intimidation, right up to physical assaults and injuries.
There was also threatening behaviour involving parents.
Mr Evans said there was variation in the action from the guidelines which came from local authorities, but there needed to be consistency.
He said the poster idea was a start and highlighted the issue, but cited a need for respect for teachers from a minority causing problems.
A Welsh Government spokeswoman said: “Any form of violence or abuse against staff in our schools is completely unacceptable.
“We want our schools to be safe and welcoming environments where teachers can get on with their jobs, helping pupils achieve the best they can.
“There is a duty is on local authorities and schools to ensure that schools are a safe environment for all. If at any point the environment within a school becomes unsafe, the school should ensure that the relevant authorities are informed so that appropriate support can be made available.”