Former mixed martial arts champion Georges St-Pierre squared off against pint-sized opponents to teach children about bullying.

The matches took place in a video game, but the lessons being taught at Moncalm elementary school were very real.

Karine Jean-Bart said bullying had recently become an issue at the school, so she and other teachers led children in creating anti-bullying messages to deal with the matter.

"We had lots of problems and we had to deal also with the police to tell them that it was really serious," said Jean-Bart.

The video game giant Nintendo found out, and decided it was a good forum where GSP could bring his anti-bullying message.

St-Pierre was bullied as a nine-year-old in the South Shore town of Saint Isidore.

Older children taunted and repeatedly attacked him, stealing his lunch money, even stripping off his pants.

He had plenty of advice for children.

"If you have lack of confidence and you shrug your shoulders and you don't look people in the eyes you're projecting an image of a victim and you will be a victim," said St-Pierre.

He said children have to learn to project confidence, even when they are afraid or nervous.

"Sometimes you cannot change your world immediately. Start by changing yourself and then the world will change around you," said St-Pierre.

He said to this day, he still gets nervous getting into the ring.

"When I go to a fight I'm scared. I'm scared that I will be humiliated, that I will be knocked out but I act, I act like it's impossible for me to fail and I'm going to win," he said.

Students appreciated the lesson, and related their own tales of encounters with thuggish children.

"It almost got to happen but I kind of like managed to escape from that," said Mumin Ahmed.

Wilson Chuong said the negative effects of bullying affect people for a while.

"It's a bad thing considering people are depressed because they're bullied and they don't know what to do," he said.

St-Pierre is hoping to return to ultimate fighting this fall, after retiring in 2013.