He is best known for writing curriculum and programming for teaching African American History at most grade levels for early 20th-century public schools.
[1] Dreer is also credited with initiating Black History Month observance in the United States, alongside Carter G.
[1] He realized in his early teaching experience that most Black students did not have an understanding of African American history, and in some cases they had a negative feeling towards the subject.
[1] Topics covered included Ancient Egyptians, the shaping of Africa, and the developments of East African nations, all of which was considered radical at the time.
[1] Dreer wrote for newspapers including the Black-owned St. Louis Argus, where he had a weekly column "Highlights of Negro History".
[1] He directed of several pageant events many of which were popular during the St. Louis Negro History Week, and these carried as memory aids for Black communities.
[8] The Dr. Herman S. Dreer House at 4335 Cote Brilliante Avenue, St. Louis was added to the National Register of Historic Places in 2009.