The concept of differentiation holds immense significance in education, touching upon aspects like access, inclusion, justice, and equality. However, it is also a complex and elusive notion, which acquires different meanings across historical and cultural contexts. This article explores the shifting reasoning about differentiation in the Swedish…

All children have intelligence in varying degrees in various abilities; Structure of Intellect (SOI) Institute tests diagnose those abilities successfully in gifted, deaf, retarded, aphasic and all ethnic groups. With a database of thousands of student test responses, materials are developed to prepare children for the future. (NEC)

This paper explores the reasons for the rapid adoption of intelligence tests by the public schools, and the historical relationship between testing and ability grouping or tracking. Case studies are presented of three California communities--Oakland, San Jose, and Palo Alto--between 1910 and 1925. These communities have been selected because they…