Hi, Julie! Welcome here--I haven't been here very long, but certainly appreciate all the wonderful insights that are on the forum, and hope that you will find some answers to your questions.
Your son is two years older than my oldest, so I don't really have specific suggestions for you, but I do have an idea or two based on our own homeschooling that might work for you at higher levels.
Harpo (7) loves the Michael Clay Thompson language arts curriculum (available from Royal Fireworks Press
www.rfwp.com ). It comprises grammar, vocabulary, poetics, and writing; the books are intended for gifted students. We're in the second year of them, but they go on up through high school level--there are sample pages online so you can see what might work for your son. As a bonus, they're very reasonably priced (and you don't need both of the student workbook and the teacher edition).
For Latin, we are using Minimus Secundus right now--if your son has any prior Latin knowledge, the Minimus series will be too easy, but it's a nice/cute introduction for kids (and moms!) with no background. We also use Esopus Hodie (available from the American Classical League) from time to time when we're feeling ambitious, and Learning Latin through Mythology by Beverley Hanlin (Cambridge University Press, available from Amazon or whomever). All three of my boys learn best when there's a story attached--so these Latin series, as well as the MCT language arts books, work really well for them.
I've been looking into science materials more these days--mostly what we have done so far has been based on nature study, gardening, and lots of library books about chemistry, force and motion, and some messy kitchen table experiments! I've been thinking about Bite-Size Physics (
www.bitesizephysics.com), which looks quite fun, but maybe isn't quite enough for someone in your son's situation? Also, have you seen "The Physics of Superheroes?" by James Kakalios --not a curriculum, but it looks seriously fun, particularly for boys! We have also done some of the TOPS science (topscience.org) modules--you might look into those, as they have lots of different topics and levels, and they use household materials for experiments (the authors were in the Peace Corps for a while, and had to teach science in Third World schools without benefit of lots of equipment--so their stuff tends to work well for homeschoolers).
Our social studies choices, at least as far as curriculum per se goes, are oriented toward Canada, so we're no good to you there.
Hope some of this might help a little--good luck to you!
peace
minnie
PS Just had another idea--Ray at Horriblebooks.com has gifted kids, and does special orders several times a year from Scholastic UK, Galore Park, and several other publishers--you might find some ideas there. He's a very nice guy, and the customer service is excellent.
