If the classroom projector is not showing the same thing as your computer's display, you may need to mirror or duplicate your display.
Press the windows key and P to bring up the display menu. Select "Duplicate" from the list.
Select the Apple menu and choose "System preferences". Select "Diplays" and choose "Arrangement". Mark the "Mirror Displays" checkbox.
For additional assistance, contact Academic Technology: (415) 405-5555, firstname.lastname@example.org, LIB 80