Reading is assigned and must be done BEFORE class. Will discuss several cases on a particular area of law - most profs require student participation. Typically students discuss the cases (issue, facts, procedure, law, analysis, conclusions) and respond to questions from profs, who will drill down and down with questions to make points. Students often prepare their own case briefs - I recommend using good professional briefs supplamented with the actual reading. This saves a lot of time.
Some profs are decent and casual in the questioning, some are beligerent a-holes who hammer away and leave you feeling stupid. Those are a small minority, but they are out there.