The modern museum has many faces, the most significant of them is the educational one. Education is an indispensable element of pedagogy, both in the family and in school. The Museum of the History of the School of Karl Ivanovich May in St. Petersburg on the Vasilievsky Island, which is discussed in the article, is the center in which historical sources that reflect the educational principles of pedagogy of K. May are concentrated. The materials suggest the history of the creation of the museum collection, analyze the activity of the famous teacher, reveal the principles of practical pedagogy on the example of the museum exhibits.