It's good to thank the school personnel and show appreciation, but I think your letter is too apologetic. It is important that you share your son's test anxiety, but perhaps you should share where your DS is acdemically at this point in time. For example, the assertion that your DS read at 2.5 would not be of particular interest to the school, but where he currently reads fluently with comprehension may be relevant. As I recall, the reading level ranges of kindergarteners were huge and change quickly through the year. Similarly with math, it may be more useful to specify which curriculum he has actually mastered.
