The imagery of scowling and shaking his head indicate annoyance and frustration at Dana. He doesn't seem to like her answer, but he only mutters about it under his breath. He doesn't care enough to talk to her about it. The imagery of the yellow chalk makes me think that the chalk is old, perhaps that it has been buried in his bag for a long time. He has to dig for it, so he's not well organized. Stevens also doesn't seem to have the motivation or the desire to become organized. He simply doesn't care.

The use of the word notorious implies that Stevens does not appreciate Dana's work ethic. He seems annoyed by the fact that "She's happy to be there," as he later notes. Perhaps her enthusiasm annoys him because of his own lack of excitement to be there.

Stevens doesn't care enough to correct his student. The imagery here conveys that Professor Stevens is distracted and lacks motivation.

By saying his smile is plastered on, the author further conveys a sense that Stevens would rather be anywhere but his classroom. He is forcing himself to be there, and he doesn't seem to like his students very much.

This imagery brings to life the scruffy, worn out uniform Professor Stevens wears. By showing how he dresses, the imagery shows us that Stevens doesn't care about his appearance very much, and that he doesn't care about his class much either. The use of the word "slings" in the next sentence also implies a lack of enthusiasm towards his class.