A.G.
I think kids get frustrated, and often take that out in physical ways on other kids. She sounds very normal!! I would add to the advice you've already gotten that I would insist that my child apologize to this boy the next time she sees him. She has to be responsible for her actions, and provoked or unprovoked, she should not have hit him. I tell my kids all the time that they have to be responsible for themselves, regardless of what people around them are doing. I would have some sort of consequence (or motivation) in mind for her to apologize. It's important, and it's humbling, so it's going to be hard, but she still needs to do it, and be sincere about it. This is a GREAT lesson for a 4 year old to learn!