A woman who sought help after her six-year-old son was throttled by an older student was told by an education official that bullying "builds character", a court heard today.

Benjamin Cox is suing the NSW government, claiming not enough was done to protect him from playground abuse that allegedly began when he was five years old.

His mother Angela Cox, from Raymond Terrace near Newcastle, today told the NSW Supreme Court that the bullying, which started nearly 13 years ago, had had a lasting impact on her son.