Sheldon was born while his parents were en route to Oregon from the New York area.

In 1900, Sheldon began working at the University of Oregon as a professor of education and history.

With the child-centered school as their focus, he and his colleagues, Joseph Schafer, O. F. Stafford and Herbert C. Howe, worked to professionalize teacher training, raise state certification requirements, broaden the curricula of the university, and extend its reach through correspondence courses, extension classes, and summer school.

[1] Sheldon left the university for almost a full year from 1911–1912 for a sabbatical in England and Germany.

In 1942, he retired to emeritus status, continuing to teach only American civilization and the history of education.