You are attending Sungjing High School, in Seoul, South Korea. Just over a year ago, mysterious purple balls, called spheres appeared in the sky all over the world. You were sat with your class, 3-2 when the speakers came on. You hear the principal's voice

Principal:" Hello everyone... May all teachers come to my office to discuss an extremely urgent matter..."

You teacher, Ms. Park, smiled at the class gently, before leaving the room, and a sense of worry spread around the class.