The Individuals with Disabilities Education Act (IDEA) is a law ensuring services to children with disabilities throughout the nation. IDEA governs how states and public agencies provide early intervention, special education and related servicesto more than 6.5 million eligible infants, toddlers, children and youth with disabilities.
Infants and toddlers with disabilities (birth-2) and their families receive early intervention services under IDEA Part C. Children and youth (ages 3-21) receive special education and related services under IDEA Part B. Here is the U.S Department of Education site for more information for families.
IDEA is a law that informs how schools provide services and it informs but is different than the Individual Service Plan (IEP).