You can use the side switch on iPad to either lock the screen rotation or to mute some iPad sounds. Tap Settings > General and find “Use Side Switch to:” then select Lock Rotation or Mute.
If Mute is selected, the switch on the side of the iPad will mute system sounds. If you choose Lock Screen Rotation, then the switch locks the screen. If you have the side switch set to lock screen rotation then the system sound control can be modified in the task bar (Double tap the home button and swipe all the way to the right.). If you have the side switch set to mute system sound, again, screen rotation can be changed by double-clicking the Home button to display recently used apps and swipe all the way to the right.