This is a tool that can help you learn from your notes. USe the tape tool to cover over the notes – see if you remember the material, and then tap to reveal the hidden areas.
It is CRITICAL that you have your Notability notes backing up to Drive, AND in the correct format. This lets you retrieve your Notes using ANY internet enabled device, and the Notes are backed up as you create each one.
Another advantage: If you delete a note from your iPad, it does NOT get deleted from Drive.