The author writes these sentences to show the variety of students in Professor Stevens' class. The author uses verbs to show that some students are trying very hard to do the assignment while others don't even try. Like the girl who keeps looking at the clock. This gives the readers another picture in their minds on how the class is like.

The author uses words like "shoots up" to show Dana's enthusiasm to be a volunteer. This gives the readers an even better image of what Dana's like.

The author uses the verb plastering to make the readers understand that Professor Stevens did not have a genuine smile, but a fake one he threw on to not seem disinterested in teaching the class.

These sentences are packed with many instances of vivid imagery. The author uses sensory details to describe how the students are in Professor Stevens' classroom. The author writes of a young man whose desk was empty except for his head. This is a scene of imagery the author writes to show the student's lack of interest in this class. Another sentence shows that the only person in this class who might care would be the overachiever Professor Stevens' saw in the front row. The author selects the word front row to show that Dana chose to sit there to indicate to Professor Stevens that she cares about the class and wants a good grade. All of this imagery gives the reader an understanding of how Professor Stevens' class is on a regular day.

This sentence uses imagery by using concise and vivid adjectives about Professor Stevens' outfit that enables the readers to build an image in their heads. The image that I built when reading this piece of text was of a very disinterested Professor who we can clearly tell does not enjoy his job by the way he dresses to lecture in a class.