I have a close friend whose kids are several years behind mine, and I bent her ear continually about this stuff. She took my advice and began afterschooling with Singapore from day 1 of first grade (and now wishes she'd done English, too, by the way). So it was just what they did from the start, and the kids thought it was normal, so there's been much less friction.
Without a jumpstart like this board or a friend with older children, it can take years for the insanity of elementary education to sink in. I started smelling a rat when my kids were around grades 3-5 but figured it out too late to do anything but remediate and try to fill in the gaps.
With math I was lucky; it was touch and go and at least one of my boys has emerged from the other end of afterschooling and interschooling (middle school at home) both good at, and liking, math. But I'm sad to say that it was too late for writing--they were too resistant. It breaks my heart because writing is so important.
For many kids, when you catch it at middle school, I think despite a parent's best efforts it may be too late.
A couple of things I've learned as a parent are:
1. If your elementary age child is hiding under the bed every morning refusing to go to school, it's more likely that there is something wrong with the school, not the kid, no matter what the school tells you. Ditch the school, pronto.
2. If your elementary age child is crying while trying to do math homework and/or if you do not understand your child's math homework, your school is probably using a constructivist curriculum and if you don't do something about it, soon, your child will probably end up hating math for good and the world may have lost yet another chemical engineer, thanks to the NCTM.
3. If most or all of your child's writing exercises have to do with connections, personal reflections, autobiographies, feelings, favorite this or that, past experiences, family, community, and hopes and dreams, your child will end up with a monumental case of writer's block, won't know how to write even if he does ever break through it, and the world may have lost yet another lawyer or diplomat, thanks to Lucy Calkins.