A teenager’s closed door can contain concentration as easily as defiance.

A closed door is ambiguous and gets read as hostile more often than it deserves. Behind it there may be homework, music, a phone call that matters enormously, or simply the need for one room where nobody is watching. Privacy is part of growing up rather than a verdict on the people outside.

Knock and ask something ordinary rather than opening with a concern. Make it clear the door is allowed and that you are nearby. Most young people come out more readily when leaving the room is not treated as a summons.