Doors or movable partitions could be closed to separate the classes, or opened to allow the entire body of pupils to participate in school-wide exercises.
To facilitate this, the building's interior layout had to enable the students to be quickly and efficiently divided into classes or brought together in a single body.
The plan fell out of favor in the early 20th century, when Sunday schools changed their approach to one in which pupils were taught separately for the entire session, eliminating the school-wide exercises.
The experiment proved successful and was taken up elsewhere; by Raikes's death in 1811, Sunday-school pupils numbered about a quarter-million, throughout the British Isles and in the United States.
The expansion to upper classes was pioneered by, among others, noted divine Lyman Beecher, who in about 1830 sent his children to Sunday school, and encouraged his neighbors to do likewise.
In 1872, a national convention adopted the Uniform Lesson Plan, whereunder all students would study the same Scriptural passage but would be taught in a manner appropriate to their age.
The Sunday-school building had to be designed in such a way that the pupils could quickly and efficiently be separated according to their various grades, and brought together for whole-school activities.
[10] John H. Vincent, an authority on Sunday schools in the Methodist Episcopal Church and later a bishop,[11] described the architectural requirements: "Provide for togetherness and separateness; have a room in which the whole school can be brought together in a moment for simultaneous exercises, and with a minimum of movement can be divided into classes for uninterrupted classwork".
Working with architects Walter Blythe of Cleveland and Jacob Snyder of Akron, he devised a plan in which wedge-shaped classrooms were separated by partitions radiating from the direction of a central superintendent's platform.
Doors on the platform-facing side of each classroom could be closed during grade-separated lessons, or opened to allow all pupils to see and hear the superintendent during school-wide exercises.
Moreover, the exclusive focus on Biblical passages made it difficult to study such things as church history and organization, missions, and latter-day issues such as temperance.