All ActivPanels in Elementary Classrooms have AppleTVs connected to them.  You can "AirPlay" your device to the Apple TV without connecting any cables.

To AirPlay from your laptop click on the AirPlay icon in the menu bar and select the appropriate Apple TV from the list. (Note: Do not select any Apple TV that has the word "room" in it because that would be an old Apple TV that is not in use anymore and will be removed from service.)