Monitorial Schools are schools where classrooms are organized with sub-groups of students based on ability. The teacher would teach the higher group of students and then let them help teach the children who were of a lower ability. First developed in the 19th Century by noted Educational pioneers, Andrew Bell and Joseph Lancaster, both from England.
Andrew Bell (1753-1832) received support from the National Society for the Education of the Poor, which was backed by the Church of England. He developed the idea of having brighter students help teach the students of lower level. While superintendent of the Madras Male Orphan Asylum in India he taught a clever boy his letters and then had the boy teach others in the asylum. Bell returned to England in 1796 and authored a pamphlet on this teaching style. Later it was adopted by several schools.
Joseph Lancaster (1778-1838) was an English Quaker and received support from the British and Foreign Schools Society. He lectured and promoted education all over England. Lancaster refused to use painful punishments but created a system of monitoring students and keeping them in check with shame. His first school in Southwark, England has over 1000 pupils. However the school eventually went bankrupt since it only survived on donations. Lancaster went to America and started another school in Baltimore, which also failed.
The Lancastrian System, was essentially where the more advanced students taught the less advanced students. This first evolved as a way to depend on less teachers due to the lack of money in his free schools.