Yes, it is possible to upload a zip file with feedback for multiple students. The key is to be sure you have the naming convention sorted. Or risk giving the wrong student the wrong feedback! So most likely you will be using a word-merge or other means of generating the feedback automatically.
- Make sure your assignment has Feedback types of both Offline grading Sheet and Feedback files
- 'View All Submissions' and then Grading Action - Download Grading Worksheet.
- This csv file will have Column A - Participant Number. This number is unique to the student AND the assignment, e.g. Participant 401, And Column B - Full name, e.g. Joe Bloggs.
- Use this spreadsheet file to create the following naming convention for your feedback files. e.g. "Joe Bloggs_401_assignsubmission_file_.pdf". As far as I can tell the underscores are important!
- Zip your renamed feedback files.
- 'Grading Action - Upload multiple feedback files in a zip', drag and drop your zip file in.
- Sit back and enjoy a well earned break.
On trialling I think you may be better off putting each feedback file in its own folder per student e.g. A folder called ' Joe Bloggs_401_assignsubmission_file_' with a feedback file such as 'JoesFeedback.pdf', but I have not tested this enough to be sure.