I am a university student of mathematics with a good record and years of experience in teaching. I teach via Skype and digital whiteboard. While we have a Skype voice conversation, the student sees on the screen a blackboard on which I am writing and explaining. I don't know if you know the format, but you only need a computer and internet connection. It is very comfortable and identical to classroom classes. In addition, I would do a personalized follow-up, that is, I could raise doubts that arise when studying and I would solve them at the moment even if we do not have a scheduled class. Miguel.