McGuffey became a "roving" teacher at the age of 14, beginning with 48 students in a one-room school in Calcutta, Ohio, and at a seminary in the town of Poland, Ohio. The size of the class was just one of several challenges which the young McGuffey faced. In many one-teacher schools, students' ages varied from six to 21. McGuffey often worked 11 hours a day, six days a week, in a succession of frontier schools, primarily in the state of Kentucky. Students brought their own books, most frequently the Bible, since few textbooks existed.