I just realized that the Earth Science Regents Prep app will crash under certain circumstances. Namely, once you finish taking a quiz and try to go to another section. I have fixed this and submitted it to the iTunes App Store. It should be approved by next Monday (7/26) or Tuesday (7/27). So, the update will be available soon. Thank you for your patience in the mean time.
By the way, this behavior, luckily, does not affect the Living Environment Regents Prep app.