I can't help you with EDM, but I have a DS-nearly-8 who is very mathy. How's your maths, or that of any other adult in the household? I ask because we and DS's school rejected the option of putting him with an older year group in similar circumstances to yours - he'd have needed to be with way older children, timetabling would have been tricky, and pace would still have been a big issue; the benefits didn't seem worth the risks. We've left him with his age-peers but he's had entirely his own maths since part way through the first year (with occasional joining in with maths games or whatever). It's worked well. Last year we really ran his maths entirely ourselves as his teacher wasn't in a position to do so (stuff she'd never taught and probably hadn't thought about for a long time!); the year before and this year his teachers set him work. Lots and lots of problem-solving, which is far more important than speeding through curriculum - but of course, going at his own pace he's far ahead with curriculum too. So it can work, if you're in a position to do the work when it doesn't work for school to...
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