How to Duplicate or Extend your Screen in Windows 10

Windows 10 – Change Display Mode

Extend – makes all your monitors act like one big monitor extending the desktop across all of them.
Duplicate – makes all of the monitors display the same thing by duplicating the desktop on each monitor.

By default, classroom computers are set to Duplicate mode. If you change to Extend mode for your class, please remember to change back to Duplicate mode as a courtesy for the next professors using the room.
If you are in a classroom and what you can see on the computer monitor isn't displaying through the projector, you may just need to switch display settings from Extend to Duplicate.

Follow the instructions below to change the display settings.

How to Change from Extend to Duplicate

-Right-click on an empty area of the desktop

-Chose Display Settings

-Scroll Down until you see the Multiple displays section and select select Duplicate these displays or Extend these displays