When connecting a computer to a projector whether it be an interactive projector or an LCD a few items to bear in mind:

 

  1. Connect the machine to the projector.
  2. Power the projector on.
  3. On the Mac go to System Preferences>Display.
  4. Ensure show mirror options is enabled.
  5. Go to Arrangement.
  6. Ensure the displays are mounted on one another.
  7. Check to ensure resolution is set to automatically optimize for the device.
  8. If no automatic option is available you can try different resolutions and see which is best (do this after focusing the projector unit).