This lesson can serve as an introduction or review of the way in which "secondary considerations" are used in assessing the nonobviousness requirement in patent law. The lesson assumes a basic familiarity with the nonobviousness doctrine. Before doing this lesson, students may wish to review the lesson dealing with Basic Concepts of Nonobviousness. Other aspects of the nonobviousness doctrine are covered in the lesson dealing with Scope and Content of the Prior Art. Students may do this lesson either before or after that lesson.