What type of aggression is okay for a 6-year-old boy to show among playmates (e.g., playing bad guys and good guys on the playground and tugging on kids' arms or making threatening gestures with sticks), and should a parent step in to stop it or act in some other way?
It's important to recognize the difference between pretending to be aggressive (as when playing "good guys and bad guys") and actually being aggressive (such as when a child threatens another outside of play). You can allow more leeway in play than in actual interpersonal behavior. A child who is "threatened" by another pretending to be a "bad guy" typically won't be genuinely scared or hurt, as long as the "bad guy" doesn't actually hit them.
It's nearly impossible to avoid "good guy-bad guy" play among little boys. They will engage in this kind of play regardless of what toys they are given or denied. However, you may notice less of this type of play if your child watches less television or plays fewer video games with these themes. It's also essential to teach children that no one is fully a "good guy" or a "bad guy." While this idea may confuse them initially, it is an important lesson over time.
When a child is actually aggressive, they are often just protecting their personal boundaries. In nature, animals set their boundaries with growls and snarls, becoming vicious only if they actually bite. Yet, we often expect children not to do this. A certain amount of "growling" and "snarling" can be okay for children. They need permission to tell other kids to back off and leave them alone.
Real aggression often arises when a child is angry and doesn't know how to express it or set a boundary with another child. For instance, one child might "bug" and provoke another until the other child lashes out. It's important to teach your child to use words to express their feelings or needs, such as, "Don't touch my stuff," or "Stop making faces at me." Coaching children in verbal expression can help them avoid resorting to physical threats and violence.
It's not effective for a child who is being provoked to use "wimpy" statements like "Please don't do that," or "That hurts my feelings." These statements may invite further bullying. A child needs to be able to give the verbal equivalent of a growl or snarl, which can be done without damaging anyone's self-esteem.
What about physical retaliation if someone does attack your child? It is important to keep this as an option because children need to know how to defend themselves. Martial arts training can help a child learn when physical defense is necessary and how to do it without causing injury.