pea, mckenzie, and all of you, fascinating thread - i also have a 7 yr old who has been this way from the very word go. the years 2-4 were particularly explosive and in fact rage punctuated every hour of the day, looking back. i have had years of dramatic meltdowns upon eg not being able to (on very first try)...tie knots, get tights on, peel stickers off objects, get spellings right first time, get homework right first time etc. motherhood has been utterly draining much of the time!!
i can't really teach her anything and thank god for school where she is much more self-controlled and does well academically - i am FULL of admiration for you ilanak for home schooling - we couldn't hack that in a zillion years!
craft kits put the fear of god into me - argh!! - and yet she loves making things and is always asking me to show her how to sew (double-argh!!), help her make a fairy house etc.
BUT it's getting better with age. and perhaps for those of you whose kids weren't like this before, it may get better soon of its own accord...i believe that a lot of it in my daughter's case is maturational and possibly to do with her prematurity - she was 10 weeks early and ex-prems are apparently v prone to excessive anxiety/frustration etc.
the key is definitely to remain calm and act like it's not a big deal. reassurance without being over-the-top is good for her - i don't over-egg the pudding any more as i spent too many years being overly sensitive and touchy-feely without much benefit.
if it's a big meltdown in her case, a time-out in her bedroom has helped on many occasions, not necessarily in a punitive way (it's clear to me these meltdowns frighten/disorientate her as much as they dismay me.) - she is a massive bookworm so i tend to put her in her bedroom firmly and calmy with a pile of books and tell her she can read until she calms down and then can come out again.
homework we have to divide into bite-size chunks and never attempt too much at any one time. i also find doing it in a public place (eg while her bro is at his football after school!or in the library)helpful as she is more controlled in public places.
she is tricky with me over such things and yet fine at school - so often the way - we mums get the flack and the teachers see the more self-controlled child! but i'm obviously grateful that she can keep it together in the school environment.
kids like this grow into bright, able and - yes! - perfectionist, high-achieving adults. i would often settle for medium-achieving but more mellow, i must admit, but hey, you don't get to choose!! and there are loads of positives (which i admit i have not highlighted here, have i!)
good luck to all my fellow mums-to-high-intensity, perfectionist kids!