I’ve been experimenting this year with a two screen setup, one projector and one 70″ LCD TV. Instead of having the same content on both screens, I use a Chromecast in the TV along with the Chromecast extension in Google Chrome.
Send one tab
By default, the Chromecast extension wants to send one tab to the Chromecast. Which opens up a neat possibility. I can start my day with an entry ticket, with the questions on the projector and also cast to the TV. When it is time to move on, I open a new tab up under Chrome. This tab is not being cast to the TV, so the project will have a different screen while the TV still shows the entry ticket questions for the classroom.
By using these two tabs, I can juggle content to either screen, or to both screens, opening up a wide variety of ways to differentiate instruction. It does fall down when showing videos, I have to use the non-cast screen or my audio only comes out of the TV.