You have two routes you can pursue when your child gets bullied at school:-
● Sue the parents of the bully
This involves getting in touch with a personal injury lawyer and providing him/her with evidence of the bullying. Such evidence can include a doctor's report describing injuries sustained by the child, medical bills, your child's testimony, witness testimonies of other bullied children, and so forth. The lawyer would then file a personal injury against the bully's parents on the grounds of vicarious liability.
● Sue the School where the bullying occurred
In this approach, you would need to establish the school staff's duty of care towards your child, prove that this duty's negligence resulted in the bullying, and show the adverse outcome of the bullying on your child. This involves providing a personal injury lawyer with medical evidence of injury and including demonstrating other adverse effects.