Supertopic

On the other hand, shifts in contextual constraints are even greater at first-level boundaries, at the beginning of a story (in narration) or a supertopic (in elicitation).

That choice would leave the supertopic Classroom Experiences open, a situation that can be represented with an open parenthesis.

There is an overarching topic, sometimes called a supertopic, and the interlocutors move through a series of subtopics related to the supertopic, slipping easily from one subtopic to the next.