What to do before selling or giving away your iPhone, iPad, or iPod touch
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
Verify that your ios device is free of the activation lock.
How to check if the activation lock is active on a device
iCloud can’t find that page
Here is some further info.
-- Learn what to do if your iOS device is lost or stolen.
-- Learn about Find My iPhone Activation Lock.
-- If you registered your device with Apple, you can unregister it at My Support Profile.
If for some reason you try to login too many times to the ipad, it will freeze up. & as you know, low you will be to recover.
You do want to be the first to set the Activation lock. This way you can at least restore you iPad should it get locked out.
Activation lock
Find My iPad
"With iOS 7, Find My iPhone includes a new feature called Activation Lock, which is designed to prevent anyone else from using your iPhone, iPad, or iPod touch if you ever lose it. It starts working the moment you turn on Find My iPhone in iOS 7."
Activation Lock for iPhone, iPad, and iPod touch - Apple Support
Undoing the Activation lock
See Texas Mac Man post in
I have restored a school ipad and was set… - Apple Community