Story of the World is a read-aloud history program that has fun activities.  It starts with the ancients and moves on through the years -- whether you continue homeschooling or not, you can continue to buy the books and read them aloud for fun.  We've used the ancients and medieval books and have loved them.  First grade is about the time to begin, although don't be alarmed if your child doesn't retain a whole bunch!  You're meant to repeat every four years, getting progressively more challenging in your studies. http://www.peacehillpress.com/index.asp?PageAction=VIEWCATS&Cat...

That said, I'm inclined to think that for first grade "social studies" you can study the people of the world and tie it into geography.  We did that quite successfully using the DK books as a jump-start.  My boys loved finding out about other countries!  http://us.dk.com/nf/Book/BookDisplay/0,,9780789402011,00.html  There's one about their celebrations around the world, too.

the sky's the limit...literally. What interest does your child have?  Moon & planets? Bugs? Volcanoes? Birds? Magnets? Human Body?  When my dd was in 1st grade, we did buy the Bob Jones Science curriculua, but it was sooooooooo boring!

So we took a topic that she liked, did a little search on the Internet and our public library, and went with that. That was so much better.  When you focus on what your child enjoys learning about rather than teaching something from "mid-air", they will not only learn more, but they will enjoy it, too.  "Learning" not "school" should be as enjoyable as possible and that is what homeschooling is all about. 

Pam gave you great suggestions for "social studies/history", and I would like to mention, too for you to find movies, that are age appropriate and to your child's maturity level. This brings history so alive! 

Check out this link...scroll a bit down and start clicking.  Some movies you can find at any rental place in your  area, your local library, and the net.

http://www.homeschoolchristian.com/Cinema/index.html