I have used Apple Remote Desktop to share my screen so I can work through topics with my students. I’ve found that they are more focussed on what we are doing this way as compared to using the overhead. I can allow them to use their desktop while observing me work through a few different examples when coding with Scratch. This worked great last semester but with our move to Yosemite I have had a number of problems.
Often when I start the Screenshare Session the screen goes black and although the mouse is active the students are unable to do anything. I searched for a few solutions and found a few mentions of using
[su_frame]
ssh <adminUser>@<computer_ip_address>
then using
sudo killall -HUP WindowServer
[/su_frame]
to quit the WindowServer service and return to the login screen. So using Apple remote desktop and the Send Unix command I could send a killall -HUP WindowServer as root user. This takes the machine out of the black screen and to the login window.
Need to look beyond this workaround and figure out why this is happening next.