Most common communication in language teaching?

While I am not entirely sure I understand your question, I know that most language teachers find that using an in-person approach, and having a small class is most effective. The benefit of a small class means the teacher will be able to work individually with students and give them lots of assistance; an in-person approach is preferable to an online class, because that face-to-face contact is very helpful in language learning. The preferred way to teach a language these days is by immersion: getting students to speak it, practice it, and to imitate a native speaker.