I'm not familiar with AIMSweb testing (I don't have a clue what it is)... but fwiw, if his scores were "all over the place" is this typical? Or does it indicate the test might not be valid or that there may be areas of strong strengths vs relative weaknessess?
I think that you're not going to get very far with *your* assessment of your ds' abilities and achievement levels. Schools like factual data. Your school has one set of data that they've collected that you have questions about. I think the start of your letter is great, but before sending it, I'd suggest considering what you want to accomplish as your next goal, and what you need to do to get there, then craft the rest of the letter.
If you're seeking more challenge in school for your ds, then it seems like the next logical step is to collect data that shows his achievement levels (and refutes the test data that the school has now). There are two ways to get that data - you could make a written request to the school, as part of this letter, that the school do further testing. State your reasons for asking for the further testing (scatter in AIMSweb test scores, test scores don't match what you've observed at home etc); or you could seek private testing to get your own set of data. If you go private, be sure you get a test that is nationally recognized. It doesn't necessarily have to be the same test the school would use, but it needs to be a test that is perceived to be reliable, and it needs to test the achievement skills that you want to prove to the school your ds is capable of.
If you decide to request further testing from the school, put the request in this letter. If you decide to pursue testing on your own, add a question about the nature of the scatter but don't say anything yet about the private testing.
The other thing you can do which I'm sure you've already done is to collect work samples from home. If you have some samples that clearly refute the test results, you could scan them in and attach them to your letter.
I would also take out some of the apologetic tone in the letter.
polarbear
