I'm not saying you can be proficient with screen in 10 minutes. Far from it. What I did say is that, if I were somebody who wanted to teach and share a session with someone, I would put a page with the following instructions to Joe:

  1) open a terminal
  2) ssh joe.student@teacherserver.net
  2.a) your password is "PASSWORD_FOR_JOE"
  3) screen -x joe.session

What else does the student need to do, besides having a ssh client?