Apple TV mirroring from staff MacBook Airs can drop the mirroring session when the machine runs out of memory. The more programs that are open at once, the more memory is consumed on the machine. Once the system reaches a threshold of high memory usage, the OS will start to terminate processes that are not "mission critical" for the system to continue to run. One of the processes that can be terminated is Airplay. So when the system runs out of memory, Airplay mirroring is one of the services that is shut down.
The best baseline preparedness measure you can take for Airplay mirroring is to quit everything that you will not be displaying for others. If you are going to show a YouTube video, quit every other application you have running, as well as every tab (except YouTube), you have open in your web browser. This way you can be sure that there is enough system memory available for the Airplay mirroring session.
Basic Guidelines for Airplay Mirroring from a MacBook Air:
- Quit all unused applications that do not need to be displayed to your class
- Close all browser tabs that are not being shown to students
- Use the On Screen passcode feature of Apple TV so that students in neighboring classrooms do not accidentally take over your Apple TV with their own mirror session