Note: This document describes using Laurel Ridge Community College classroom teaching stations and projectors. All of these concepts can be applied to any Windows computer that has more than one display of any kind, be it a projector, a monitor, or a television type display.
Keyboard shortcut for switching between duplicate and extended mode: ⊞ Win + P
When presenting content to a classroom, some professors may prefer to have exactly the same information appearing on both the teacher station's monitor and what is being presented by the classroom projector. This would be "duplicate display" mode.
Some professors prefer the content displayed to the classroom to be different from what is being shown on the teaching station. Common reasons for this would be the use of either Microsoft PowerPoint's Presenter View or Google Slides with presenter notes, which can be configured to show the presentation on the projector, but the presenter notes on the teacher station. This would be "extend mode".
Switching between different display modes can most easily be done by holding down the Windows key on the keyboard (it is in the lower left hand corner and looks like the Windows logo) while tapping the P key to switch between different modes. As a note, there are two other modes that are likely not needed in a classroom setting, which would be only displaying content on either the teacher station monitor or the projector while leaving the other display without content. More information about this can be found on the Microsoft help document: Connect to a projector.