Here's why. The Federal Special Education Law, called the Individuals with Disabilities Education Act (IDEA), includes a clear definition of learning disabilities. It states that "Children with specific learning disabilities exhibit a disorder in one or more of the basic psychological processes involved in understanding or using spoken or written language. These may be manifested in writing, spelling, or arithmetic. They include conditions that have been referred to as...dyslexia, etc. (Need I go further?) This law demands that every school in every city in every state must provide a "free and appropriate" special education programs for all children with special needs.
Now, while it's unlikely, it may be that this little girl has dyslexia that is not serious enough to have a significant negative impact on her learning. In this case the school does not have to provide special educational services. This family should have an independent evaluation (the law gives them the right to do this) to find out if that's really the case. The school system might be saying the child is "doing well enough," when she's really not. She may be a gifted child with LD who's "only" working at grade level. This is a tragedy, but it often lets schools off the hook. Don't accept that reasoning, and argue the point that this little girl's potential for higher level learning is blocked because of her learning disability (dyslexia). If it turns out that she is not eligible for an individualized educational plan (IEP), because the LD is not having a significant impact on learning, she may be eligible for what's called a 504 plan, which comes out of another Federal Law (Section 504 of the Rehabilitation Act) that guarantees that she is not treated with prejudice because of her disability.
There's a lot to consider here, but there's a lot at stake. At any rate, use the law to make your case. It was written to cover situations just like this. If you want to know more about LD and the law, go to ldonline. Good Luck. No--Good LAW.