During the institutionalization of mass schooling in the 19th century, teaching large groups of children became both a necessity and a matter of regulation. For officials and inspectors the systematization of classroom interactions was important for effective results. However, while systematization could bring about the constant attention of children and their uninterrupted work, interactions themselves were difficult to control. Rationalized models of classroom organization provided alternatives for managing large groups before age grading became the dominant pattern of organizing interactions. The contributions in this volume explore diverse paths of transition towards modern classroom organization in different countries, allowing transnational perspectives and comparisons.