Notability is an app that lets you download PDF documents, ie. class notes, and work on them. You can highlight, write, or draw on them. It also gives you the ability to record information that you can later visit an add onto. The drop down box allows you to organize your notes by subject. My son said this has been vital to his science class this year. He has taken the teacher's notes and been able to add his own notes, drawings, and etc and then printed it. He said it is so much easier in class to just be able to listen to her teach the lesson and then go back and write later. This is an inexpensive app for just $.99.
CourseNotes is a similar app that lets you take notes or write papers directly on your iPad or iPhone. Then you can share your notes with others just as you would share any other content on your phone. It enables you to print and my favorite part is that you can bookmark your notes and sync it with your calendar. So if you take notes in science and there is a test over those notes you can mark that and get reminders to study. You can also remind yourself of assignments that are due. This app is a little more expensive at $3.99.
Of course there are many more apps to help our children to day to study, like the flash card apps, that I will be looking into.
My only advise is to check out each of the education apps fully before purchasing. Make sure it is an app that your child can easily navigate and will utilize. Every child learns differently and studies differently. So make sure the app will benefit your child's learning style.