My son was diagnosed with a language disability at age 6 (the end of K), by the school. I referred him for an educational, psychological, and speech and language evaluation. Like your son, he had initial speech delays, had a very difficult time learning his letters, couldn't rhyme and scored very poorly on all school based reading assessments for phonemic awareness and pre-reading skills.

Your description of his current struggles confusing numerals, replacing words using context as he reads, spelling difficulties are all hallmarks of a reading disability.

Schools don�t conduct testing to "diagnose". They evaluate to determine if the child fits into any of the categories outlined under IDEA, federal special ed law. Be sure not to use the word dyslexia, unless your school uses it. Because dyslexia is not a federal category, schools often "refuse" to use the word. Instead, use words like disability in reading. Likewise, ADP is not a category, but disability in language processing is.

So - how to find out what is going on. Generally, I would recommend starting with the school and writing a letter requesting a full educational evaluation. Mention your concerns: Difficulty with reading, spelling, writing, overall lower academic performance than expected etc. If he has organizational difficulties, word finding problems, memory issues, mention this too. The district must evaluate in all areas of suspected disability within about 60 days (varies by state). You'll get a copy of the evaluation report that should include a description of the tests, the results (in standard score and percentile rank), interpretation, analysis and recommendations. You will meet with a team that includes special educators, evaluators, general ed teacher to determine if your child is eligible for special ed. If he is found eligible you will write an IEP that outlines current level of performance, goals and service. It sounds like he may already have one for speech - if so, this would be an amendment.

Sometimes school evaluations are not very good. If you are not satisfied, you can request an IEE independent education evaluation at the district's expense once they have had their turn.

As an alternative - if money is not an issue, you can have your child privately evaluated. Given his history, I would suggest a neuropsychological evaluation given by a professional that specializes in working with children with learning disabilities. I would also suggest a full speech and language evaluation that looks at both oral and written language. Often time teaching hospitals, universities have LD units that do this kind of testing. If there are any LD schools in your area, they may be have a list of good evaluators.

In the meantime, I urge you to read "Overcoming Dyslexia" by Sally Shaywitz. Also, you may find these resources helpful:
Is it a reading delay? http://www.greatschools.org/special-educ....gs?content=743
Special ed evaluations http://www.greatschools.org/special-education/LD-ADHD/evaluation-an-overview.gs?content=665
Early signs of a reading disorder http://www.greatschools.org/special-educ....gs?content=739
Fact sheets on dyslexia http://www.interdys.org/FactSheets.htm
LD forum http://millermom.proboards.com/index.cgi#general
LDonline - resource for learning disabilities http://www.ldonline.org/