Sorry, I don't know of any particularly good resources for what you need--although there is that "Genius Denied" book that is featured on the Davidson site that might discuss it. But I just was struck by the letter (and I suppose one might expect this sort of thing in writing, because the principal is probably cautious about what he puts in writing) in that it looks like he's prepared to cite various studies to back up handling it how they want to--which I would bet is what they're already doing. (Such as citing the "Fountas and Pinnell benchmarking system"--showing you that he has expertise, which would be good except from the tone of the letter and what is said I'm betting he's going to try to shut you down from asking for more even if you think your kid really needs it). But on the other hand it does sound like the teachers are trying to be helpful, so I would be sure to express appreciation for that even while also expressing that DS5 needs/wants more (remember, DS, or you on behalf of DS, not just you--my own DH unfortunately talked about wanting to 'push' DD in a meeting last year when it is her pushing because he has not read so much on these things, and in that setting I think it totally undercut what we were saying about trying to get more advanced math work for DD, because DH did most of the talking, as he is wont to do
--so be careful). Good luck!
