But what had previously been verbal bullying boiled over on May 27, resulting in a savage beating where the boy was hit 15 times in the head while the teacher was out of the room, according to his mother.
One of the boys who had been "hassling" him for weeks grabbed one of his friend's belongings and tried to leave the room with it, but the boy stood in his way and told him to give it back, she said.
"[The bully] just pummelled him," the mother said.
The boy told his mother he felt like vomiting after the attack, and had a splitting headache.
"They didn't get medical help for him. They put him on the bus and sent him home."
The school called then called the mother, who questioned why they had put him on the bus before calling her, and was told it was because her son had said he was "fine".
"Since when do you listen to an 11-year-old regarding medical stuff? That's not for an 11-year-old to decide," she said.
"He could have had a seizure, my goodness, he could have fallen over. A lot of stuff could have happened."
When the mother later took her son to the doctor, it was found he had suffered a concussion. She then filed an assault complaint with police.
In a statement, principal Mary O'Regan confirmed the boy was given permission to travel home by bus instead of being collected by his parents.
"We have reiterated to all staff that any incident that impacts on the head or neck should be referred to our medical room, with the next steps ideally decided in conjunction with parents. We are confident that this would not happen again," she said.
"Regarding the incident, we can also confirm it was fully investigated by the school and our findings were shared with the police who were comfortable with our process and outcome.
"The Board of Trustees has not received any correspondence regarding this matter and would be very happy to review the school's actions if asked to by the parent."
She said the boy who did the hitting was stood down after the incident.
O'Regan said the issue should not be labelled "bullying" as it was a one-off incident, but confirmed the boy's mother had visited the school previously to complain about bullying issues.
The mother said there needed to be stricter handling of such issues, and felt there was little being done to make her son feel safe.
She believed children were being taught to be "punching bags".
Over the past few months she had noticed her son become "moodier" and "angrier", and said he was more prone to outbursts.
A police spokeswoman said police received a report of the assault the next day, and a specialist school community officer had had "extensive contact" with the school and families concerned.
"Police are satisfied that the school has dealt with the matter appropriately, with the alleged perpetrator held accountable for their actions and a plan put in place to help ensure the victim feels safe at school.
"Police believe this to be the most appropriate course of action given the nature of the incident and the ages of those involved."
The mother said she would like to see a "more robust method of dealing with these children and pull in the parents to be proactively working to change the behaviour and help the children be accountable for their actions and choices".
Ministry of Education deputy secretary for sector enablement and support Katrina Casey said the incident had been reported to them.
"All students deserve to feel safe at school, and this is something all schools take very seriously," she said.
"Bullying and violence are complex issues with multiple causes, and every school is different. Schools have clear policies and procedures in place to respond to unacceptable behaviour in the school environment. If help is needed, we work alongside schools to help develop a response plan to any incidents.
"We are aware of the incident that occurred at Maidstone Intermediate, and we contacted the school's principal to offer our support. The school is working with all the families involved as well the appropriate agencies in managing the incident."
Children's Commissioner Andrew Becroft said school protocols were important, and in place for sound reasons.
"It's disappointing to hear when they are not followed, especially in serious cases where a student has been injured and was put in a vulnerable situation," he said.
"Generally, there are internal and external processes in place for dealing with issues of bullying and violence, including referring to the specialist Youth Aid division of the police."
