This piece is written about literature classes, but with a few details changed it applies as well to classes in every other subject.
A musician who shows up for rehearsal without having learned the song slows everything down and makes the rehearsal much less productive. It’s a drag when everyone has to wait for the members of the group who are unprepared. On the other hand, when all the musicians show up knowing their parts, the rehearsal is enjoyable and the group makes great progress fine-tuning their performance.
In the same way, a student who shows up for a literature class without having done the assigned reading slows everything down while basic questions are covered: “What does that word mean?” “How are those two characters related?” “What happens in Chapter 2?” The discussion cannot make progress until everyone knows who the characters are and what happens in the assigned chapters. But when everyone shows up having done the reading and made notes, ready to ask higher-level questions, then the discussion can move into the really interesting bits: interpretation, analysis, and reading “between the lines” for a deep understanding of the text.
So if you arrive in class unprepared, you are not just letting yourself down and limiting your own learning: you are letting your classmates down and limiting their learning, too.
Don’t be an irresponsible classmate. Do the assigned reading. Make notes. Look up the words you don’t know. Prepare interpretive questions to ask in class. Your will learn more, your classmates will learn more, and the lessons will be much more enjoyable.