How to anonymize submissions and ensure each student gets exactly one chance to submit?

Question

I am teaching a subject for a group of students I have not met before, and the exam coming up. It is a 14-day take-home exam. My previous experience with examining similar students indicates that there is a somewhat widespread problem of failing to answer in sufficient detail or sufficient rigor. (My subject is rather "mathematical", but the students are rather "not mathematical", so they are not used to mathematically rigorous thinking.) When reading their answers, I feel I would like to ask about the omitted details*, and I suspect quite many of the students would answer my additional questions correctly. If only I could provide them this chance...

I thought of allowing the students to submit their drafts early. Then I would glance over the answers and comment on those who should be expanded or detailed, without indicating whether the content of the current answer is correct or not. I think this would achieve the goal.

However, there is the problem of anonymity. Normally, the students submit their answers to an online system which anonymizes them and only then do I get to evaluate them. The system cannot be used for early draft submission, though. Another way would be for the students to send me e-mails with their drafts, but that would breach anonymity. Question: Could you recommend a solution of how to anonymize the draft submission? I also would like to ensure that each student is only given one chance to submit the draft (which seems like an additional difficulty in designing an anonymized system).

*_{You could suggest to formulate the questions absolutely precisely so that there is no way a thoughtful student would miss what the answer should be and how detailed it should be. I am trying this to an extent (taken to the extreme, it would make the questions awkward), but this does not always work as well as I would like. Also, what I am trying to evaluate is primarily not the mathematical rigor but the general understanding and some other things. As long as a student can answer correctly and in sufficient detail (regardless of whether this is right away or after additional questions/comments from me), I feel the student deserves a good grade.}

Answer 1

This third-party documentation on Moodle "assignment" activities suggests that it's possible to release feedback files to students without revealing the student identities to the marker; but I've never tried it.

Answer 2

Use an LMS

If you are at a university or college in the US, it is very likely that you are using, or at least have access to, a Learning Management System (LMS). The major systems I am aware of include Canvas, Blackboard, and Moodle. Most LMSes have some kind of assignment management system which allows instructors to collect, grade, and give feedback on student work in an anonymized manner. If your institution uses an LMS, I would strongly recommend that you learn to use it (in particular, that you learn to use the assignment management system). The LMS may or may not make your life easier, but if your institution uses an LMS, then students should be proficient users of the system, and working within that sytem will make their experience smoother and more unified.

Use Dedicated Software

If your institution does not use an LMS (or if you refuse to use the LMS for some reason), there are dedicated services for assignment management. I have used both CrowdMark and GradeScope in the past—I found both to be far superior to the alternatives built into Moodle and Blackboard, but your milage may vary. Both of these systems make it relatively easy to grade student work anonymously (indeed, it actually takes a little bit of work to de-anonymize student work).

Do Something ad hoc

N.I.'s answer suggests a rather complicated scheme using DropBox (or some similar file sharing service) and anonymous keys. Such a system could certainly work, though it sounds like a lot of extra work for the instructor (even if you skip the third-party—I am not sure that the double-blinding is really necessary, more on that below). If I were to implement such a solution, I would probably do something like the following:

1. Create a write-only directory on some file sharing service (for example, DropBox documentation: [1], [2]).
2. Give each student some kind of unique key which they will use to "sign" their submission, and a second unique key for viewing the feedback. This could be further anonymized by sending the keys through a third party, but I don't think that this is really necessary.
3. Have students sign their work using their key (e.g. make the key part of the filename) and submit their work to the write-only directory.
4. Modify the submitted documents to provide feedback, use second key to encrypt the file (e.g. on the Mac command line, the command zip -e [filename] will create a password-protected zip file), and upload that file to a publicly viewable repository (e.g. on DropBox).

This process is similar to N.I.'s, but has the advantage of being a (in my opinion) a lot easier to implement at the cost of being a bit less secure.

Don't Sweat It

Have students use "normal" procedures to submit drafts in a non-anonymous manner (or semi-anonymous manner, e.g. have students use their student ID to identify their work). I understand the desire to grade blind, but (1) I don't think that this is as important as N.I.'s answer makes it seem and (2) I don't think that it is really feasible, anyway—you can likely recognize the handwriting of many of your students (or their writing style) already, hence even a double-blinded submission process is unlikely to be truly anonymous. Given that real anonymity is likely impossible, I don't think that there is a huge problem with following the path of least resistance, and simply collecting work as you would normally collect it.