They had the same day's class. Amy was late on the first day of school. Amy lives in Manhattan. One day before school, Amy downloaded Google maps, entered the destination in advance, looked at the route, what kind of transportation can be used, and then made plans on how to get there fastest and cheapest. She found the nearest subway station to walk by, so she turned on the mobile phone navigation to go to the nearest place according to the navigation tips The railway station, because it is the first day of school, is not familiar with the surrounding environment, so she should always compare the map with the real scene nearby. It took about half an hour to get to the subway station, 15 minutes later than originally planned. So she was late for school.