by ben reynolds.
Hi Gary,
You don't say which version of Moodle you are using.
What was called in 1.9 "Advanced uploading of assignments" allows both students and instructors to upload multiple files. The single file upload is not nearly as useful. You can change the assignment type in any version of Moodle.
Of course, what you really want is 2.4's ability to download all student files as one zip, along with a gradesheet. You make corrections in the downloaded files and upload as one zip along with the gradesheet.