Learn what a national anthem is. A True Book: American History series allows readers to experience the earliest moments in American history and to discover how these moments helped shape the country that it is today. This series includes an age appropriate (grades 3-5) introduction to curriculum-relevant subjects and a robust resource section that encourages independent study.This book explains what a national anthem is; recounts how and why Francis Scot Key wrote The Star-Spangled Banner, including the history of the specific flag to which he referred; and describes how his poem eventually became the national anthem.