What is the key assessment tool used to determine eligibility for special education services?

The correct choice is developmental assessment, as it plays a crucial role in determining a child's eligibility for special education services. Developmental assessments are comprehensive evaluations that gather information about a child's developmental milestones and skills across various domains such as cognitive, physical, social-emotional, and language development. This holistic approach allows educators and specialists to identify specific areas of developmental delay or need, guiding the decision-making process for eligibility.

Standardized testing, while informative, typically measures specific skills and may not capture a full picture of a child’s abilities or challenges in a naturalistic context. Behavioral observation provides valuable insight into a child's interactions and behaviors but does not systematically assess developmental strengths and weaknesses. Curriculum-based assessments focus on measuring a child's progress against specific educational goals rather than evaluating overall developmental status, which may limit their utility in identifying needs for special education services. Thus, developmental assessment is essential for a thorough understanding of a child’s developmental profile when determining eligibility for special education.