The one with all the bits cut out of books? That was the room of the giggling blonde girl. She did a speech in there about 'remember the time I changed my Facebook status...' but she also did that in the main hall so you may have seen it elsewhere.

Things happened in all the rooms, but only at certain times during the rotation - you should have met/seen each of the girls in white in their own space and a scene in the Director's Office?