On p. 4 of Teaching Spanish, Rivers has a chart of the process involved in learning to communicate, as she sees it. Skill-getting and skill-using are the two dominant categories. Under the first are Cognition (knowledge) which includes Perception and Abstraction (internalizing rules relating categories and functions, in her words and key to my use of rule-getting and rule-using to characterize this understanding of what is involved in learning to communicate).
Under skill-getting we also have Production/Practice that involve Articulation and Construction both being forms of practice.
Then the second dominant category, skill-using, has Interaction which involves Reception and Expression (what we call passive/active or intake/output or comprehension/production). Interestingly, the latter two components of Skill-using have wedged in between them a category called Motivation to communicate.
On pp. 238-239 she discusses rules thus:
“Skill-getting for oral or written communication is based on knowledge of the way the languages operates (cognition). Many grammatical rules are the same for speech and writing e.g. the agreement of subject and verb in certain conventional ways: [examples from Sp.]” She goes on to say that some rules depend on the degree of formality, but the list from Sp shows clearly that she is thinking of the typical rules published in textbooks of the elementary (years one and two) level.
Then on p. 239 she writes:
“Learning the rules and conventions of written language is reinforced by writing out examples and applying the rules in new contexts, thus developing awareness of the abstraction and control of its graphic manifestation. For written language, this activity parallels the oral practice exercises which help students develop flexibility in structuring their oral expression. Writing things out helps with the organization of material to be held in memory and clarifies rules at points of uncertainty. It gives concrete expression to abstract notions. Al of this is, however, merely preliminary activity which is pointless unless it is serving some clearly understood purpose of meaningful communication.”
I didn’t pursue this so far as to find the section where she discusses at length the oral practice since I feel the above quotes more than adequately demonstrate her reliance on abstract rules and their manipulation to achieve proficiency.