Each morning, four children stand barefoot in a line and proudly sing the national anthem as the Thai flag is raised outside their school, perched on a finger of land surrounded by the sea. They are the last pupils left at the school in Ban Khun Samut Chin, a coastal village less than six miles from the edge of Bangkok that is slowly being devoured by the waves. Here is a glimpse into their grim present and their aspirations for the future.