I work in several schools that are 1:1 with iPads. One of the biggest complaints from teachers is how cumbersome it is to grade on an iPad. Yesterday I was researching for an easier way and ran across a great app, MarkUp by Learnbat, Inc.
What MarkUp does is pure genius. When you purchase the app and create an account, the app assigns you an email address. Students then submit their assignments to the MarkUp email address. (Don't worry, it's not another email address you have to check!) The app automatically strips the attachment from the email and posts the assignment (attachment) in the MarkUp app. The teacher opens the MarkUp app and corrects the assignment. Return it to the student via email -- the other best part is coming up! The app recalls the email address that is associated with the assignment. So teachers do not need to keep track of student emails either!
I encourage you to try this app out. I showed it to 3 teachers this morning and they were pretty excited for it. They will be testing it for a week and I'll let you know more about what they think of it!
MarkUp by Learnbat, Inc. https://itunes.apple.com/us/app/markup-annotate-grade-sign/id628143995?mt=8