Why does the aft support john scopes

The American Federation of Teachers (AFT) is a labor union founded during World War I that focused on getting teachers better pay and more rights in their profession. One of the factors that the AFT fought for after World War I was their ability to teach without the government interfering with their classroom.

This is exactly what happened to John T. Scopes. His teaching of the theory of evolution lead him to be arrested, as this broke a Tennessee state law. The AFT supported him, as he was willing to challenge government interference in with the science curriculum.