Two weeks earlier, she’d sat through a geography lesson she almost didn’t pay attention to. Then she was standing on a beach in Thailand, watching the ocean do something no one else noticed. Ten-year-old Tilly Smith had about ten minutes to convince the grown-ups around her she wasn’t wrong. This is the true story of the day a school lesson saved a hundred lives.

SOURCE LIST:

1. UNISDR (UN Office for Disaster Risk Reduction), "Tilly Smith: In disasters, lessons save lives" (2016). Primary source for the full narrative: Tilly's classroom lesson about tsunamis, recognizing the warning signs on the beach, alerting the security guard, the evacuation of the beach, the aftermath, and her return visits to Thailand.
2. The Sun (archived by the International Tsunami Information Center / UNESCO-IOC), "Girl's sea warning saved a hundred" (Jan. 2005). Primary source for the estimate that roughly 100 people were saved and that Mai Khao Beach was one of the few Phuket beaches where no one was killed or seriously injured.
3. Associated Press, syndicated report (Jan. 1, 2005). Corroborates the timeline, the Smith family members, the evacuation sequence, and the events immediately following the tsunami.
4. Wikipedia, "Tilly Smith." Background on later recognition, including the Mon Quotidien award and asteroid 20002 Tillysmith. Recognition details should be verified against the underlying citations.
5. U.S. Geological Survey (USGS) — 2004 Sumatra–Andaman Earthquake. Magnitude 9.1 earthquake, tsunami science, and overall impact figures for historical context.

A NOTE FOR PARENTS:

The 2004 Indian Ocean tsunami was one of the deadliest natural disasters in recorded history, affecting fourteen countries. This episode intentionally keeps the wider tragedy gentle and unnumbered for young ears while never pretending it didn't happen. If your child asks more, the sources above are a good starting point — as is the lesson Tilly herself now teaches: knowing the warning signs (water pulling far out OR pushing in and in without retreating; frothing at the surface; a roaring sound) and moving immediately to high ground.