Do Not Disturb
Do Not Disturb is an easy way to silence iPad, whether you're going to dinner or to sleep. It keeps FaceTime calls and alerts from making any sounds or lighting up the screen.
Turn on Do Not Disturb. Swipe up from the
bottom edge of the screen to open Control Center, then tap
.
When Do Not Disturb is on, 
appears in the status
bar.
Configure Do Not Disturb. Go to Settings > Do Not Disturb.
You can schedule quiet hours, allow FaceTime calls from your Favorites or groups of contacts, and allow repeated FaceTime calls to ring through for those emergency situations. You can also set whether Do Not Disturb silences iPad only when it's locked, or even when it's unlocked.