Step One: Go to the assignment and select "Launch External Tool"
Step Two: Select "Upload Submission"
Step Three: Select "Choose File" (unless teacher is accepting non formatted text input).
Note: you'll want to have saved a PDF or MS Word (docx) copy of your paper to either Files on your iPad or your Google Drive before this step.
Step Four: Select "Browse" and then change "Locations"
Step Five: Select the appropriate location (iCloud Drive, Files on your iPad, or GoogleDrive). If Google Drive doesn't appear, tap the three dots in the top middle/left area and turn Google Drive on. Again, make sure you've already saved your paper in the correct file type in that location before this step. If you have trouble with Google Drive, you can always save to Files directly on your iPad. It's easy and almost always works more quickly.
Step Six: Select your file. If you don't see it, double check that you saved it where you think you did! Last chance to also make sure you're grabbing the correct file type. Turnitin only can read PDF or MS word docs (docx).
Step Seven: Change the submission title if needed and select "Upload and Review."
After that, you'll be able to review your submission (make sure everything looks okay!), and then "Submit to Turnitin"