Watch and listen to this story:
It is based on a true story about a British girl called Tilly Smith.
In December 2004 she was on holiday in Thailand with her family. She was 10 years old.
Lessons save lives: The story of Tilly Smith
Tilly Smith learned about tsunamis in a geography lesson two weeks before the tsunami from her teacher Andrew Kearney. When she was at the beach she recognised the symptoms of a tsunami and alerted her parents. The beach was evacuated and she saved more than a hundred people.