Ahhhh-- but is this about proving your point about the two curricula?
Or about getting what your DS seems to need from them?
Those two outcomes may well call for quite different strategies.
For the latter, might I recommend sleight-of-hand?
"Oh, yes, we've never been especially pleased with Everyday Math. That's why we've opted to enrich his learning at home-- so that he wouldn't have to be in remedial coursework elsewhere."
Or allow them to dictate to you what would constitute "proper remedial action" over the summer? You know, so that he's "on track" with his classmates in the fall.
In other words, I'd go in with statements that clearly ASSUME the placement you believe to be appropriate, and express confusion/cooperative attitude about "working together" toward that goal.
But that's me.
