Sociolinguistics 6, Exercise 2: home, class, recess

The domain model explains it: Fishman proposed a domain-specific model, later
refined by Blom and Gumperz, in which bilinguals choose a language by
location and topic. The source's own example is exactly this child.

What the markedness model adds (Myers-Scotton): speakers choose the language
that clearly marks their rights and obligations in the conversation, and when
no clear, unmarked choice exists they code-switch to explore options. It
explains the cases where the domain does not decide, such as mid-conversation
switching. The source notes that many sociolinguists object that language
choice is not entirely rational.