This study examines the purpose and practice of "adjustment rooms" established in special education classes in Los Angeles public schools in the early twentieth century. The establishment and practices associated with adjustment rooms are a local example of broader international trends related to the classification and streaming of schoolchildren. In this study, I argue that the function of classification and the structure of normalisation were embedded in the practices of adjustment rooms. Since a diverse group of children were being placed in ungraded rooms in Los Angeles and were not being properly educated, the adjustment room practice was initiated by identifying educable children from among them. New educational methods, which were gaining attention in progressive education at the time, were thus developed to compensate for educational delays. The goal of the adjustment rooms, which were designed to educate "backward" and "misfit" children, was to provide auxiliary education and return them to regular classes in a short period of time. Thus, on the one hand, the adjustment room had the function of promoting normalisation to the standard student model. On the other hand, the adjustment room functioned as a "clearing house" to categorise children, deciding their fate according to ambiguous criteria of educational potential. While attempts were made to return educable backward and misfit children to regular classes, "feeble-minded" children were judged to be uneducable and were removed from the adjustment room cycle, thereby promoting internal exclusion within schools.