What is this computer monitor type things called and where is it sold?
It’s not really called anything, except for a second monitor. That second monitor can be a regular flat screen monitor, or an overhead projector. We use two monitors so we can keep one of them private, and the other public that our students can see. The “official” term is called using a dual monitor setup, and again, that second monitor can be anything. Certainly your computer needs to be able to accept two cables, but when it does, you can set your display settings so that you are either displaying the same exact thing on both (2 monitors, same image), or you can set up like your instructors have it ( 2 monitors, different image). Your instructors set it up so basically it is one giant display over 2 monitors, and you have to drag your mouse from one to the other.
