"All this Facebook stuff has lifted the bullying problem to a different level and it affects the mental well-being of teens," Pereira said.
"But it can start in pre-school and kindergarten. It's a social cruelty and girls who get bullied become depressed, while boys are more likely to go into defence mode."
And the reasons girls bullied were different from the reasons boys did so.
"They are like chalk and cheese. Girls are much more subtle, boys more obvious. You can hear boys bullying from 50 metres," Pereira said.
"Bullying happens in the largest and the smallest schools and it's just as sophisticated in rural schools as in city schools.
"There's no getting away from it, bullying happens in single-sex, co-ed, private and religious schools as well as public schools. This is a human nature problem made more efficient through technology."
Pereira has spent 41 years in education and holds a BA Diploma of Education from Macquarie University, Sydney, and a Masters Degree from Fordham University in New York.
He is the author of two books, including Why, Just Why is My Child Being Bullied? He has been running workshops for more than 20 years, including in Singapore, Hong Kong, Korea, China and Australia.
"Is this problem getting worse? Yes," he said. "Bullying has become a 24-hour experience because cellphones, computers and the internet mean at any hour of the day or night kids can be sending bullying messages."
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However, Pereira emphasised that 95 per cent of children treated one another with respect, "most of the time".
"If a vicious text message is sent at 10pm, would you know your daughter had sent this message? For the recipient, this message is going to consume them at school and they won't be able to concentrate on their classes."
The question most parents asked was, "why is my son or daughter being bullied and how long is it going to go on?"
"Bullying can begin in the first five minutes of the school year," Pereira said. "Don't be blaming the teachers. You need to work in partnership with teachers and you need to bring bullying to the attention of schools.
"A lot of teachers are saying, 'we don't have bullying', and I can understand that. They can't be everywhere at once."
Pereira uses real-case scenarios to highlight his sessions, some with tragic endings where the person commits suicide. His is a behind-the-scenes look from children's viewpoint, not academics.
"In the worst-case scenarios, parents go into denial; you need to be open to evidence. Parents are generally the first to know something isn't right and there needs to be openness on both sides, school and home.
"If you don't have conversations with your children, the situation can build up to suicide."
Bullying had become even more sophisticated, with an Indonesian website advertising bullying services on the internet, all within the price range of a teenager, Pereira said.
"There is a Middle Eastern chat app (the Dannevirke News has chosen not to name it) which offers to send anonymous messages with no right of reply," he said.
"I found out about this app at a prestigious Dunedin school and if they know about it in Dunedin, they know about it here in Dannevirke."
Dannevirke High School principal Di Carter said bullying often took place late at night, in the early morning or at the weekends.
"Teenagers are vulnerable in their own bedrooms, but we can't turn off their (home) internet," she said. "But now, after these workshops we will have more strategies to turn this around, but we want bystanders and good kids to help."
And why do boys bully boys?
"The number one reason is because the target is smart, he's different, even in Asia. He likes working," Pereira said.
"The most destructive word in boys' bullying culture is 'he's gay'. All their teasing words have a homophobic overtone.
"Boy bullying is all about teasing. Boys can't share their emotions if they are on the receiving end. In the United States they are driven to get a gun . . ."
Pereira said to be successful in dealing with bullying there had to be a preventative approach.
"We need to deal with it before a crisis occurs," he said.
"I've taken age-appropriate stories and given teachers a bank of stories covering a whole range of critical scenarios. Dannevirke High School has a new process they are implementing."
Pereira said his research used children's own stories.
"My research isn't statistics, and teachers here in Dannevirke were putting their lesson plans to prevent bullying into practice from Wednesday."
There was no magic answer, no silver bullet, Pereira said.
"But the answer is educational, with a need to take a preventative approach."