A useful acting class gives you material to prepare, a clear way to approach it, time to put the scene on its feet, and feedback you can apply in another pass. The exact format changes by class, but the work should move from explanation into practice.
You may break down a script, rehearse with a partner, work in front of the group, review a self-tape, or adjust after direction. Expect to prepare outside class. Bring your sides, know the circumstances, make a choice, and stay available when the scene changes.
The room should also have clear standards of respect. Direct notes are part of training. Demeaning comments, hazing, forced personal disclosure, and attacks on an actor’s worth are not. A teacher can say the work is unprepared or the choice is not serving the scene. They should not turn that into a verdict about who you are. The goal is to see where your process holds, where it breaks, and what to practise next.