Hendrik Willem van Loon wrote lots of books. His most well-known book is "The Story of Mankind". He wrote it and also drew many pictures and maps for it. It is a history of the world written for children. "The Story of Mankind" won the first Newbery Medal in 1922. People have read "The Story of Mankind" ever since it was first printed. Hendrik's son Gerard wrote more chapters for the book after more history had happened. Later, other people wrote even more chapters. The book now has about 500 pages. Hendrik also wrote lots of other books for children and young adults.