I think we can all agree, the most important thing is being able to locate our children!
I think in the case of an emergency for a current user, the alerts may be top priority! This comes to the user in a notification, text, or phone call depending on the urgency of the alert. Beyond that, the actual first—most important thing our user wants to know is, "where is my child?". The first thing a parent will do is seek the location of their child. Once they locate them on the map, the next question goes to inquiring about the bus location and whether or not it will be arriving on time. The user can then connect both the location of the child, and the bus—on the same map. The app will send a notification the child has made contact and entered the bus. The app will prompt the user to use the "child tracker" which was modeled off the "pizza tracker" used by Domino's Pizza. The tracker is a fun tool that shows the child in route to their destination. From there, the final important step is receiving two notifications the bus has arrived, and the child has exit the bus. Really, you can see the child first, then the bus, then the profile and customization—which also targets a specific child, then messenger, calendar, and beyond that would be the about and contact pages.