I want to know whether there is any necessary entity (quality/property) in the traditional classroom teaching that cannot be done without a physical classroom with intended students. Please keep aside the administrative responsibilities such as minimum teaching hours in classroom, availability in office, maintaining attendance of students etc.,
Afaik, most of the tasks that a professor (any lecturer) can do in the classroom can also be done without classroom with assembled students, nowadays, with high availability.
For lecture, a professor can publish her recorded video lectures to students. For query solving or interaction, she can use the Q&A site for her students. Announcements can also be streamed in a similar way. I'm referring to the sites such as Google classroom, piazza, slack, etc.,
In such a case, I'm getting the doubt whether there exists a necessary entity that a professor cannot provide without (her direct presence) a classroom teaching.
If such an entity exists, then what is that?