FAPE & LRE
The law that lays out the rules for special education is the Individual with Disabilities Education Act. Two of the most important terms in the acts are FAPE and LRE.
FAPE stands for a Free and Appropriate Public Education. Exactly what those words means has been litigated many times. Basically, they mean that children with disabilities are entitled to a public school education that addresses their unique needs with the services that they need to make progress in their education. To learn more about FAPE, check out this article which has a lot more details about the law.
LRE stands for Least Restrictive Environment. Children with disabilities are entitled to a free and appropriate public education in the Least Restrictive Environment possible for them. Restrictive refers to how segregated the classroom is. A school that only has children with special needs is the most restrictive environment while a general education classroom with no support is the least restrictive environment. In between the two extremes are general education classrooms with special education support and small pull out groups of just children with special needs. Most children are served in variety of different environments during the day depending on their needs in a particular subject area. The goal of special education is inclusion, not segregation and LRE is the part of the law that spells that out. To learn more, read this article on LRE.