What version-control system is most trivial to set up and use for toy projects?

Question

I teach the third required intro course in a CS department. One of my homework assignments asks students to speed up code they have written for a previous assignment. Fact

Answer 1

Regarding permissions, an outside service wouldn't require time from your university's IT staff.

For example, Bitbucket (using Mercurial) now allows unlimited private repos with up to 5 users. I'm guessing each new weekly pair of students is working on a new project together, which means they can just initialize the repository, add the other user, and away they go.

If they are not working on a new project every week, permissions would have to be removed and added, and I'd encourage them to have multiple repos (one per account) on Bitbucket so each student has continued access. (This would be a good idea anyway, but for only week-long projects, it may be simpler to just have one student account own the repo and the other with permission.)

Regarding which VCS, I believe Mercurial will be best given your platforms—TortoiseHg being particularly good for new users to explore, if they're unfamiliar with (and you don't have time for them to learn) command-line interfaces.

Specific to your situation, the advantage of DVCS is their copy on the university server (if there is one) is a fully-fledged repo. You may find it convenient for you or TAs to have access, which should be simpler to setup and would last all semester instead of change weekly.