The institute employed three types of classes, teaching special branches of knowledge, the arts, and pedagogy.

[2] The originator of the enterprise was Col. Homer B. Sprague, Ph.D., at that time, head master of the Girls' high school in Boston.

[1] It began with a few instructors, mostly from Boston, and a small number of pupils, who wished to push forward their studies in special directions.

Its first and largest building, called in honor of the naturalist who first established a summer school on Penikese Island, "Agassiz Hall", was built in 1882, and first occupied for the session of that year.

By 1905, though, there came a recognition that its services were no longer needed as good schools opened in all parts of the country, where teachers could receive proper instruction at less cost than to travel to Cottage City.

No buyers could be found at that time for the real estate, and it went into the possession of the savings bank, which held a mortgage upon it.

The most prominent new feature was a "School of Methods", placed under the direction of Andrew W. Edson, the agent of the Massachusetts board of education.

This department, every year since, held a session of three or four weeks, with 12–15 educators in Methods of Instruction in the ordinary branches of U.S. common schools.

These subjects were: Arithmetic, blackboard sketching, drawing, geography, history, kindergarten, language, physiology, natural science, pedagogy, psychology, penmanship, physical exercies, school management, and vocal music.

Altogether, between 1889 and 1894, about US$5,000 was expended upon the property, early all of which was paid from the extra earnings.No tuition money was appropriated for these permanent improvements.