Application

I have went through quite a few apps. I see my students having the same difficulties that my own 5 year old does. On all of the free apps-there is a place for you to click it for a full version or to unlock boards that you can play. One of two things happen- either they click it and don't know know what to do to get back to the app or they want something that can only be played on the full version. Any suggestion?