They are meant to prep students for both learning how Java works as well as the AP exam. Writing methods is a fundamental component of Java and this gives students practice with both writing methods and testing them. The way we've designed the problems to work is to be very easy to get immediate feedback. The AP exam does have complex method traces, but many of the unit test problems get more difficult as well. Additionally, teachers can create their own Custom Content problems at whichever level of difficulty they like.