When you edit files on your Chromebook it will save to your Google Drive.
Google Drive is a cloud-based storage system that allows you to access your files from anywhere you have access to the internet.
Google Drive
From the Launchpad/Clever/Rocketship click on Google Docs.
To create a new document click the “+New” button then clicking “Google Doc.” Rename the file to what you'd like it to be called.
Once you have shared a file from Google Docs you don't have to re-share once you update... your teacher will be able to see your edits in real time.