Children to bullying others are not feeling good about themselves, maybe sarcastic, have passive/aggressive behaviors. They usually pick on kids who have traits that they feel they are lacking and may be jealous of that child. Its okay for parents to check into their kids phones, computers, backpacks, etc., just to make sure things are okay. Whether being the bully or being bullied, most times the child doesn't feel able to talk with their teachers about the problem; so parents need to be watchful for both issues.