When submitting an assignment, you must grant view access so your teacher can see your document.
To share a document, press the blue share button on the top right of the screen (while you have the document open):
Press the "get shareable link" option:
The link will be automatically copied to your clipboard:
You can copy and paste the link into your assignment submission box. Your teacher will now have view access to your document. Please note, if you delete your document your teacher will lose access to the file immediately.
Share a file with a specific person by entering their email address in the "People" box.
Saving the File in Microsoft or PDF Format
To save the file so you can manually upload the document like a regular Microsoft files, please see this guide.
Additional Sharing Options
Please review the Google Drive Help Center for additional sharing options. Help Center.