As a public high school strings teacher, I really want to like and use this app, but as it stands now I just can't and don't. The last update to it was almost two years ago, back when iOS 8.3 was out. As of this writing, we're at iOS 10.2, and as the others have mentioned, there are stability issues. All my students have school-issued iPads, and this app crashes at startup on an unacceptably large percentage of their devices. When trying to register, the app also more likely than not didn't recognize their book codes, and they all had to resort to entering their ISBN numbers instead (which added to the hassle of trying to get everyone set up). The recent updates to the Essential Elements Interactive website (like the All-Music option for recording music not found in the books, and the other updates to the assignments tab) haven't been rolled over into this app yet, which is truly a shame because they could really help me out with playing quizzes and other assessments (not all my students have access to a private internet-connected computer at home with a mic.)