IDEIA239 provides for a “free and appropriate education” for all children with disabilities. The key word here is appropriate. Your child is entitled to an appropriate education---one that is tailored to your child's special needs. Your child is entitled to an appropriate placement---one that will allow your child to make educational progress.
The problem is that the determination of what is appropriate to the needs of your child is not always straightforward. Determining which services and interventions are appropriate for your child, and therefore which ones will be provided for your child, is a collaborative process that may involve considerable negotiation.