Bring your textbook to class each time. My function is not to 'speak' the book to you, but to focus the discussion onto the most significant points, to enrich the material covered in the book, and to clarify it. If the book isn't clear, ask me to explain it. If I'm not clear, ask me to explain it in some other way. Applying the formal techniques of logic to a vague philosophical argument can help to clearly display the controversial parts of the argument.
Symbolic statements are free of vagueness and ambiguity.
There shouldn't be earthquakes or murder or any other evil in the world. One reason for their disagreement is that it's so hard to tell just what the two sentences are really saying. But if the sentences are translated into symbolic logic, then the translated sentences will be precise. With precise sentences it is much clearer whether the conclusion does or doesn't follow from the premises. If the conclusion doesn't follow, then it will be clearer just what else must be assumed to make the conclusion follow.