Dyslexia is very hard to define! In fact, a recent entry on Facebook said, "My son’s school just told me there is no such thing as dyslexia! I’m dyslexic; how can they say there is no such thing?"
What the school probably means is there are many ways dyslexia can affect a child and it is more beneficial to the child to figure out what the specific problem is and address that problem. (At least, we hope that’s what they meant!)
Some people think you have to see letters backwards before you are called dyslexic. But, that is not necessarily true. That is a common misconception about dyslexia. There are some dyslexics who do, but certainly not all of them!
Formal definitions of dyslexia basically mean that a dyslexic child
In many public school systems, if the child has not already been taught these skills using research-based teaching methods, they do not provide an Individualized Education Plan (IEP). The child must show that proper instruction is not enough to help them learn these language skills. (They did not "respond to intervention.")
At the point the school decides the child did have appropriate instruction but failed to learn, they can then qualify for an IEP. Schools may not use the word "dyslexia." They will more likely say "specific language learning disability." Some schools feel that dyslexia is a medical diagnosis and not an educational one.
For a great pamphlet about the signs of dyslexia see, Is My Child Dyslexic?
There are a number of related articles here at SchoolFamily!