In the very beginning of the year when I'm introducing students to rhetoric and stylistic devices, I use this assignment to help them learn how to identify devices. I first have them listen to the speech (usually a video off YouTube) where they can follow along and mark up the text.
Then, with a partner, students have to find examples in the text, and then we go over them in class. It's a fun activity and really makes students much more aware of rhetoric. I also help them outline a rhetorical analysis (they don't actually write the essay) but we discuss which devices would work well together for analysis and connection to JFK's purpose for the speech.