It depends on the age of the child, as to what your reaction will be with regards to a bully. But the most important thing is that you take action and not just leave the matter.
Where toddlers are involved, it may be easier to act.
Talk to the staff at the school immediately when you pick up or download your child.
Ask your child every day whether something has happened at school.
Primary School and High School may not be so easy, because your child does not want you to act, fearing that it will aggravate the situation.
Contact your child’s class teacher, Grade Head or Head Master. Make an appointment with the Principal and discuss it. Write an email and bring it to the attention of the school. This will ensure you have proof that you brought it to their attention, should something go wrong?
Contact bully’s parents, if the school does not address it, but usually a bully’s parents do not want to believe their child is capable of such a thing.
Remove your child from school if it persists. It may sound drastic, but your child’s whole future being is affected by a bully !!