Since your son likes History, Konos has some mini unit studies that might be just what you are looking for.
You could begin with "Explorers"- we built a viking ship while reading about Lief Ericson.
Then on to "Settlers", where you build a model of Jamestown, and then finish the year with "American Revolution". Each of these units are designed for 9 weeks, but could easily be stretched out- there are so many great activities, books, projects, and suggestions.
www.konos.com- Look under History's Heroes.
It’s about hands-on activities capturing children's attention and increasing their retention. It’s about teaching a child, not a curriculum. It’s about fun and laughter and shaping memories. It’s about creating a love of learning that lasts a lifetime. Mary Pride, author of The Big Book of Home Learning, calls KONOS "the greatest set of home school activities ever!" We think you will too.