Well, I didn't make this discovery; my boss did! The Showbie app is free and is a place that my class can turn in assignments. I can write on their PDF files they've sent me, can add a text message on the PDF, and put a voice note reply to what they have sent. One of the students gave our class a tutorial today of the extra features in Showbie, like adding stamps to images and PDF files! Photo editing is a part of the app too, and adding video clips to posts. One of the students just sent me a voice text in Showbie asking if she can show the class tomorrow how to add a video text in the Showbie app.
A real plus is that I'm the only one who sees their comments, and posts. This is much different from Edmodo, which is a class page where all the students can see each others' posts. Serious business to have a place to get immediate feedback and store all work! So cool!
This app makes turning school work in via email seem old-fashioned!