Have you considered making up your own curriculum? I promise, it's easier than it sounds.
Get a book like "What your Xth Grader Needs to Know"
http://www.amazon.com/What-Your-Fir...mp;s=books&qid=1277182767&sr=8-1or use the World Book list:
http://store.worldbook.com/typical_course_of_study.htmlYou might also be able to find a course of study for your local area or state if you look for it online.
All you have to do then is find materials at your library (or on your bookshelf) that follow one (or all) of these general paths. But since *you* are selecting the material, you can make things as challenging as your kids need them to be.
I know this works fine because we did it. I was an emergency homeschooler when we pulled our 6yo out of 1st grade nearly 3 years ago now, and since I had no time to research curricula or do a lot of shopping, this is what we did. It actually worked amazingly well, especially for a gifted young kid who was desperate to learn.
It allows for fitting the needs of your children very specifically. In subjects our DS adored, I cranked up the challenge level. He did a version of junior high geometry that got him over his post-school "I hate math" phaase. In subjects that he wasn't that into at the time--like American history--he read books that were geared to his age level. He got the basics covered quickly on stuff that didn't interest him and he was at or beyond age-level in every subject.
We just fit a weekly library trip into our schedule (which you may do already) to get lots of books, and I made sure to look over the list of stuff a 1st grader was supposed to know once every couple months to be sure we weren't veering way off course.
But really, it was fun and easy and it allowed us to be a lot more child-led. We did a lot of reading aloud and discussion.
No pressure.
But it can be done if you want to dump the prepared curriculum and go a bit more off-road.
