Help with screen comand

[stan]

I have used the screen command in the past, but it has been quite a while.
I am trying to set it up on an Ubuntu machine to allow other users to
"shadow" my session as a teaching tool. I found this link:

https://unix.stackexchange.com/questions/163872/sharing-a-terminal-with-multiple-users-with-screen-or-otherwise

But I am having issues making it work I have run

screen -d -m -S multisession

followed by

screen -r multisession

And, indeed this does put me in a session, but I get no response to the
CTRL A keystroke. Should this not put me in the command prompt (: at the
bottom of the screen?


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