The entry is an insult to the profession. I hope you are not, because word usage is a reflection of our culture . Looking into and agreeing on word usage helps separate essential from secondary. Off the top of my head, I can think of three scenarios in which mathematics as the subject matter will also play a role. In loose terms the scenarios can be formulated thus The teacher and the students meet over the network.
Classroom becomes an association of learning and teaching individuals.
Mathematics resides with the teacher. Residence may not be physical. The teacher is where the students are. Classroom remains a conventional classroom. Mathematics resides with the teacher.