Alan Kazdin & Carlo Rotella:

Let’s say you find out that your child is being bullied by a schoolmate. Naturally, you want to do something right now to make it stop. Depending on your temperament and experience, one or more of four widely attempted common-sense solutions will occur to you: telling your child to stand up to the bully, telling your child to try to ignore and avoid the bully, taking matters into your own hands by calling the bully’s parents or confronting the bully yourself, or asking your child’s teacher to put a stop to it.
These responses share three features:
1) They all express genuine caring, concern, and good intentions.
2) You will feel better for taking action.
3) They are likely to be ineffective.