If actors are born and not made and talent cannot be taught, then what is taught in acting classes? Not very much, in most cases, I'm afraid. Too many acting classes are filled with games and exercises to make the students comfortable with being on stage and intereacting with one another. I confess that many of the classes I taught at the University did the same. And that is because beginning acting classes often attract many students of limited talent and experience and that in an academic setting you want as many students in class as you can get. It is a matter of survival. But these exercises have little or nothing to do with how to improve as an actor or how to become a professional actor--the two reasons besides networking why one should take an acting class. Acting classes (and acting curricula at academic and professional schools) most often are much concerned with various kinds of script or character analyses which are rooted in Stasislavski and Stanislavki-based teaching such as The Method or approaches by Adler, Meisner, Hagan or other notable acting teachers. Now it has been years since I read Stanislavski, but I do not recall where he advocated such analyis. He did describe exercises he used to retrain the Russian actors of his time. All teaching based upon his writing, emphasises these exercises, especially affective memory, as the key to effective acting. Much of what a student gets in acting classes is an indoctrination to the approach being taught. But so far we have not got to acting. The most benefical things done in acting classes is the presentation of scenes and monologues and having them critiqued and repeated to make them more effectibe and the introduction to techiques such as those needed for effective acting on camera, or to be a more effective cold reader or auditioner.
Well, that is about it. And that is why actors take classes for networking more than for instuction and why I think experience is more important than instruction.