Clayton, MO (KSDK) - Some celebrated Flag Day by taking part in the world's largest swimming lesson.
The Shaw Park Aquatic Center hosted the record-setting event in Clayton Thursday morning.
Similar events across the world were happening at the same time, hence the name, the "world's largest lesson."
Last year, an estimated 20,000 people participated.
Organizers hold the event to raise awareness for swimming safety.
KSDK