Give her the schedule of when the International Space Station goes over! Can she explain how it, and the Moon and Sun, for that matter, go up from one horizon, and down the opposite one, every day? How do the heavenly orbs rise in the east and go down in the west... and come back up in the east again, if the world is flat?
Encourage her to think this out! She must have spent her school days in a trance. There are anatomy students who would gratefully learn about human anomalies from a study of her cranium.