What grade is he in? A nine year old could be anywhere from third grade to fifth grade (and that makes a big difference).

Does the school do any regular achievement testing? If not, I think that you should pursue some academic testing. DD was tested twice at age 9 on two different writing tests. She didn't write more than a few sentences within the time limit and on the second test (the TOWL) it wasn't even enough words to be scored. The test is scored based on her age and at age 9 they would expect several nicely put together sentences (and that would probably only be average).