Or you can use Primary Pad. Primary Pad is very similar to Google Docs. It was designed for schools so students and teachers could collaborate on the same documents in real time. You can upload files and export once you are done. If you choose to use Primary Pad make sure you export your documents when you are finished. Your pad will erase after 30 days unless you have a paid account.
Check out the tutorial below from the Primary Pad site.
If you are interested in using Google Docs or Primary Pad in your classroom please let me know and I would be happy to help you. If you are not using Google Docs yet and you would like to learn how please let me know.