Calendars can be used in a Split View to view two apps simultaneously on iPad. For instance, you can view your e-mail and schedule events in Calendars. To enable Split View:
- Open an app.
 - Swipe up from the bottom of the screen to open the Dock.
 - On the Dock, touch and hold the second app that you want to open, then drag it off the dock.
 - When the app opens in Slide Over, drag 
 down.    
For more information about Split View, visit Apple's official website.
Note: Split View can be used on iPad Pro, iPad Air 2, or iPad mini 4.