There are many ways to go about collecting work from students but this is one method that works very effectively.
** Submitting work with a Printopia Virtual Printer
If you haven't checked out the blog post on Printopia, it's worth a read. You'll find it here...
Printopia installs on your Mac. It allows you to set up "Virtual Printers" so that anyone can use the Print function in an app and send the content directly to a folder on your Mac. If you have a DropBox account then you can add a virtual printer that delivers content directly to any folder in your DropBox.
It's an invaluable, simple and effective way to collect work from students. Virtual printers appear on the Print menu in any iPad that's on the same wireless network. Let's say you have students working on a project, Set up a virtual printer that collects the work in a folder you've called "March Projects" in DropBox (check out the blog post for details on setting up a virtual printer). When your students submit work they simply "Print" it to the March Projects virtual printer. Go to the faculty room, open your DropBox account and all the student submissions are there.
It's so easy to setup virtual printers that you can just set up a new folder and virtual printer every time you need students to submit work and keep all the submissions organized.
** Returning work with Evernote
There are many ways to return the work. Personally, I love Evernote and have each student share an Evernote Notebook with me. I can then easily annotate the work and even add voice comments and then return the work to the student's Evernote folder without ever touching any paper in the process.
Note that you can also use Evernote for the entire process by designating a shared folder in your Evernote account and having the students submit the work that way. There's no lack of options...