I often find whole paragraphs that are fluff, and I point this out to the students. In particular, when I do heavy editing on their earlier papers, I make an effort to let them know when their writing tells me nothing, nothing new, or nothing at all. These broad, non-specific sentences can be very sophisticated, even from graduate students who can be very good at writing a lot of BS, but I want more. I show them in my comments where they can be more concise, more concrete, and more precise. Therefore, I point out where they have said something, and when they’ve said nothing with the intention that building detailed writing will indicate understanding of the material. I reward the precise—the writing that says something. I tell them not to write a sentence that doesn’t provide content; when they can do that, I believe they understand the material.
The relationship between writing and learning happens over the course of a semester. I don’t have evidence yet, but I have observed that when students are forced to write a very concise answer to a relatively broad question, that those students who understand the concepts can write concisely. Conversely, when they don’t understand the concepts, their writing becomes vague, flowery, unclear or imprecise. Therefore, my interpretation is when someone writes a fluff sentence, they don’t understand the concept.
The example below consists of the first paragraphs of two papers. Each writer examines rationalism, but one response offers a vague paragraph while the other response demonstrates a more precise reply. The vague paper says nothing and does not take a position because the writer didn’t have one, which is a reflection of not understanding the concepts. See the attached PDFs for my comments on both papers, including the ideas that I gave to the writer of the vague paragraph for ways to increase its precision and my comments on content and wording to the more precise paragraph.
Vague Paragraph
"To get to the point, I feel that rationalism has had more influence
on modern psychology. This is mostly due
to the ‘active mind’ that rationalists believe in.
The active mind ‘acts on information from the senses and
gives it meaning that it otherwise would not have’ (156).
It seems like the part of the brain that is doing this ‘acting
upon the information’ is innate. Humans will make associations
between events and object without any conscious effort, therefore ‘giving
meaning that it otherwise would not have.’ But even more
than this, there is a structure to the way that humans encode information.
In cognitive psychology there are models of how information is
encoded. Hierarchies are drawn to show how people associate ideas
from broad topics down to small characteristics of objects or other
things, and although these are theories, there is support for them."
Vague Paragraph Example 
Precise Paragraph
"Rationalism has influenced modern psychology
tremendously, and early rationalists like Spinoza, Leibniz, Kant,
Herbart and Hegel are just a few who have contributed their ideas
to psychology. Rationalists believed the mind was active, therefore
it arranged the information gathered from the senses and detected
intricate ideas and concepts that otherwise are not encompassed
through sensory experience. Other important concepts of this approach
include self-actualization, emotion and passion, alienation, threshold,
and the idea of psychology being experimental."
Precise Paragraph Example
