Introducing English Linguistics

wanna digress for a second
and talk about aggregate production func-
tions, which will be a piece of the Static Neoclassical Model. 
(MICASE LEL280JG051)
The reasons why these instructors so explicitly mark their digressions is
that if they do not, students might not only become confused but think
their instructors are disorganized, confused, and not good at teaching. In
formal writing, violations of the maxim of relation are even more strictly
penalized, and are seen as markers of poor writing.
Manner
Clarity of expression is highly valued in what we say and write. For
instance, someone going to a public forum on global warming expects
information on this potentially technical topic that is understandable to
a general audience, not scientists already quite familiar with the subject.
This is why the excerpt below on this topic contains so much metadis-
course – expressions, such as My talk will be split into four sections, that com-
ment directly on how a particular piece of discourse is being organized
(other examples of metadiscourse are in boldface): 
But what I’d like to talk to you about uh this afternoon just uh briefly
because we only have forty-five minutes is uh studying climate change
from space. And my talk will split into four uhm sections. I’ll spend a