Yes, because I was bullied relentlessly at school and it has affected my whole life. On the plus side, it has helped me identify whether the incidents are bullying or not and whether they could escalate into bullying.
I think a lot of school bullying problems stem from children with a low self esteem looking for weakness in others which is then exploited as it makes the bully feel better.
Small incidents are overlooked and dismissed as "banter" and when the whole thing escalates, some adults respond with bullying the bully into submission which never works.
Thinking about why the bullying has happened is what I'd probably do first and then attempt to help my child understand that their behaviour had been abhorrent. Not easy to do with a child at any age, since I have come to believe that all humans are not above lying to meet what they feel their needs are unless conditioning has taken place to understand it is wrong.
Example.
Child A is a capable child who wins everything is always top and is perhaps a bit of a know it all. Group B do not like this, their parents discuss this with them and agree child A is an insufferable know it all. They should be taken down a peg or two. They say child A is spoilt and parent needs to parent better.
Child A comes home every night upset that they just cannot make friends because they don't fit in. Their parents dismiss the other children as bullies and try to explain to school what is happening. Parents of child A are dismissed by school who say there is nothing they can do to force the others to include her aside from small class groups.
The class groups don't transfer to the playground. Child A immerses themselves in learning extra things, they read a book at playtime having given up trying to make friends. They spend hours playing the piano or doing sums and as a consequence get very good at both. This sets child A apart even more.
By the time year six arrives, child A is way, way ahead of their peers in every way, their parents having found alternative groups out of school where they have older friends with similar interest. Child A auditions for the school play and gets the main part. Child A wins several music and sport medals at school as they took every opportunity to do any activity going because they didn't like being ignored.
Child A is in a 'head to head' class competition and every child in the class is cheering for the other child against Child A. Child A gets so upset that they don't manage to 'win' and the whole of group B whoops and cheers at their misfortune. Child A hits out at the nearest child. Child A receives serious consequences.
Child A's mother is in the playground at pick up and hears other children laughing and stating loudly that Child A was beaten on a test and she hit Child X and how they all laughed and are so happy that she was sent to the head. The other parents start to laugh along but notice the mother and look away. How on earth does one begin to sort that out retroactively?
Which set of parents are responsible? What could school have done to stop this happening? Where do they go to 'fix' it.