Irony refers to a rhetorical device in which an author expresses a statement or a feeling that is the opposite of reality, or the opposite of what the audience would expect to hear. The impact of the device lies in the difference between the two statements. In this case, we can imagine that a speech on the best way to press a shirt is probably not very interesting, which points towards the statement being an example of irony.
In Eugenia Collier's short story “Marigolds”, the author uses flashback and juxtaposition to create the narrator's voice and present a particular point of view. The narrator uses flashback to show her memories and feelings