In Robert Sigmon's article published in the Spring 1979 edition of the Synergist, Sigmon presents three fundamental principles of service-learning and tools for best practice. He also lists the different education programs that have grown in the United States since the 1960's, and points out that service-learning is rarely utilized in comparison to classroom and career-based programs. Sigmon's three principles are: (1) those being served control the services provided, (2) those being served become better able to serve and be served by their own actions, and (3) those who serve are learners and have significant control over what is expected to be learned. He also lays out the four basic constituencies in service delivery, which are: (1) those who acquire services, (2) service providers, (3) technology developers, and (4) resource providers and policy makers. Lastly, Sigmon provides a service task check list chart to help others in their service learning.