His farming was unsuccessful and he returned to education as an English teacher at New Hampshire 's Pinkerton Academy from 1906 to 1911 , then at the New Hampshire Normal School ( now Plymouth State University ) in Plymouth , New Hampshire . Ultimately his farming proved unsuccessful and he returned to the field of education as an English teacher at New Hampshire 's Pinkerton Academy from 1906 to 1911 , then at the New Hampshire Normal School ( now Plymouth State University ) in Plymouth , New Hampshire .