How did intelligence testing affect the grouping of students in schools?

The introduction of intelligence testing in the early 20th century significantly influenced the rise of ability grouping in American schools. Educators began using these tests as a scientific management strategy to separate students into classrooms or courses based on their actual or perceived ability levels.1

This practice was intended to facilitate more accurate student placement and identify talent, with advocates believing it would promote fairness and opportunity by allowing students to be evaluated on their intelligence rather than their background. However, the implementation of these tests often led to the segregation of students along racial and socioeconomic lines.21

Critics have long argued that intelligence tests can be culturally biased, favoring students from affluent backgrounds and discriminating against less privileged groups. Consequently, the use of such tests for grouping has been a source of significant controversy. In some instances, students assigned to lower-level tracks based on these assessments were rarely reevaluated or moved to higher tracks, which opponents argue created a cycle of inequality and, in some cases, functioned as a form of de facto racial segregation.31