Start a session on behalf of another user

I am the owner (administrator) of a 10-users a/c.

As the administrator, I often have to start a class if an instructor (the user) is a bit late. It will just make sense for me as an administrator being able to start that class on behalf of that user a/c. Currently, I have to log out from my admin a/c, login as that user first. After that I have to log out from that user and log back in as admin. This is very crumblesome.