The Scopes Monkey Trial dramatized the great debate over the teaching of evolution in America's public schools. By the 1920s, many people had accepted the theory of evolution proposed by Charles Darwin (1809–1882). His theory stated that all life evolved from lower forms. Many Christians, however, continued to believe in the biblical story of creation, in which God created humans in one single act. This belief is known as creationism. This debate was an important divide in the United States between traditional values (which supported creationism) and modern values (which supported evolution).

In 1925, Dayton, Tennessee, teacher John Scopes (1900–1970) was arrested for violating Tennessee's law against the teaching of evolution in schools. He had responded to a challenge by the American Civil Liberties Union (ACLU), a free-speech protection group. The ACLU offered to defend anyone willing to teach evolution in Tennessee in violation of the state's...