Privacy

Has a sign that reads, "Keep out.  This means you!" suddenly appeared on your child's door?

It's natural for middle graders to want more privacy as they grow older.  They're beginning to see themselves as unique individuals who need more space.  Also, changes in their bodies during puberty may make them want to stake out an area of the house as their own. 

Suggestions: 
The next time your middle grader shouts, "Just leave me alone" and slams the door, consider taking his advice.  He may be trying to say, "This room is my private area."  Having a private place can help him cool off and relax.  If you haven't already established rules such as "Knock before opening a closed door," consider doing so.  Tell your middle grader that you respect his need for privacy and expect the same treatment in return.  Chances are he'll understand where you're coming from.  Allowing your child to have privacy doesn't mean he has complete control over the room, however.  Let him know your expectations on how the room is kept (dirty clothes in laundry basket, no trash on floor, etc.).