1. A computer controlled method comprising: presenting a workspace window responsive to a relationship data structure that represents a comprehension state; presenting a first instance-representation that represents a first separately-movable instance object and a second instance-representation that represents a second separately-movable instance object; dragging said first instance-representation; detecting when said first instance-representation is dropped within a threshold distance of said second instance-representation; identifying, responsive to detecting, one of a plurality of spatial relationships between said first instance-representation and said second instance-representation; selecting an operation responsive to said one of said plurality of spatial relationships; modifying, responsive to said operation, a composite object in said relationship data structure, said composite object incorporating an entity/relationship object represented by said first separately-movable instance object and an entity/relationship object represented by said second separately-movable instance object; and presenting, in said workspace window, an instance-representation that represents said composite object as modified.