Supported Submission Types
To work correctly, student submissions must be in Google Docs.
CoGrader can only grade Google Docs created directly in Google Classroom or attached from Google Drive.
Works:
Google Docs is created directly in Classroom or attached from Google Drive.
Doesn’t work:
Word documents (.docx)
PDFs
Handwritten or image uploads
Google Slides, Sheets, or Drawings
Files uploaded from Drive or as any other attachment that is not a Google Doc
If a student submits using any unsupported file type, you’ll see this message:
“Can’t grade. Submission is not a Google Doc. Click here to download and add manually.”
You can actually click that message to download the submission and then upload it manually if needed.
Why This Happens
Common causes include:
Students uploaded files instead of creating Docs directly in Classroom.
Students uploaded multiple files, including the Google Doc, but the Google Doc is attached second, and CoGrader is picking up the other unsupported file.
A Word or PDF file was attached instead of a Google Doc.
Tip: When creating assignments in Google Classroom, advise the students to submit using “Add or Create → Docs” to make sure all student work is readable by CoGrader.
Quick Fix
If students already submitted unsupported files:
Click the error message in CoGrader (“Can’t grade. Submission is not a Google Doc”).
Download the file.
Reupload it manually in CoGrader
Other Common Issues
“Can’t grade. Change the permission settings of the document.”
If you see this, press Sync once (or multiple times). This often refreshes file permissions.
If that doesn’t help, make sure:
You’re signed into the correct Google account.
The student’s file is shared with Editor access.
Google Drive and Classroom APIs are enabled in your school domain.
Summary
Best practices for smooth grading:
Require students to submit Google Docs only.
Have them create files within Classroom, not upload from elsewhere.
Press Sync if you see any access or permission errors.
Avoid:
Word docs, PDFs, or handwritten submissions.
Assignments that allow multiple file types.