Many of the students that came to the Fifth District Normal School in Maryville were already teachers at rural schools. These uncertified teachers came to the Normal School to acquire certification and to ensure the standardization of education of Missouri students. For many years, the Normal School's largest enrollment was during the summer time when these uncertified teachers were not holding classes. In one summer alone, enrollment was around 1,000 students.
The Training School began the same time as the Fifth District Normal School, allowing Normal School students to teach grade-school children and gain practical experience in teaching. The Training School classrooms were originally located on the first floor of the newly-constructed Administration Building. Later, the Training School would be remained the Horace Mann Laboratory School, which still exists today.