Award-winning Edmodo for iPod touch, iPhone, and iPad makes it easy for teachers and students to stay connected and share information. Use your iOS device to send notes, submit assignments, post replies, and check messages and upcoming events while away from the classroom.

Teachers can post messages, keep tabs on recent assignment submissions, and grade assignments. Students can view and turn in assignments and check their latest grades. Class discussions can be conducted securely, both during and outside of school hours.
Edmodo Web SiteEdmodo Support
http://www.edmodo.com/

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What's New in Version 3.6
Edmodo 3.6 introduces file sharing on both iPhone/iPod and iPad. Other apps, such as Pages, Mail, etc. can now open their documents in Edmodo, which means that Edmodo uploads them to your Library or Backpack; from there, you can attach them to posts and assignments.
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a detailled desciption of the new features (with screenshots)
http://mgleeson.edublogs.org/2012/12/17/edmodo-just-got-a-lot-better-on-the-ipad/