Arnold Gesell is known for what significant contribution to school psychology?

Arnold Gesell is widely recognized for his significant contributions to the fields of child development and psychology, particularly through his work in creating normative assessments for children. He developed a series of developmental schedules that provided benchmarks for typical child growth in various domains, including motor skills, language, and social-emotional development. These assessments were pivotal in establishing norms that professionals could use to gauge a child's development relative to their peers.

By laying the groundwork for understanding developmental milestones, Gesell's work has had lasting implications for school psychology, helping educators and psychologists identify children who may be at risk for developmental delays or disabilities. His emphasis on normative data has aided in creating a more systematic approach to assessing children’s developmental progress in a school setting, making his contributions foundational to the practice of school psychology.