Go Pileus might be a great tool for students collaborating on a project to share files.

To use the app just drag your file onto the gray box. What appears next is a short url that you can share with anyone who wants to download the file.

If you have not set up an account, your url will last for 30 minutes. If you create a free account you get 1GB free space and your url will no disappear in 30 minutes.