Invalid testing

A young man I am working with is learning to read.  Will he and I have enough time before the school puts him in special education class?  I am not opposed to these classes.  They can really help some children.  The problem is once in them, it is hard to change the label.  This child has shown great improvement.  I wish I could work with him 4 or 5 times a week instead of 2 times a week.  He tests just a little above retarded.  Someone, with a master's degree in social work,  has observed him is an informal setting. This individual says the testing is inaccurate.  It is not the schools fault this child does not test well.   Some children just do not test well.  Will have to see where this will go.