I've had this one for a while, and even read some of it to the kids, but then set it aside as it wasn't "rigorous" enough. Time to bring it back out, as I think it will add a pleasant expansion to K12's Human Odyssey.
Had this recommended to me on a homeschooling message board. It looks like exactly what I want right now. I think this would go well with The Magic of Reality, which we keep meaning to read in it's entirety, having read chapter 1 three times. Somehow it always gets misplaced (ahem, Cyrus. It is not a book you should store in your bed), and then we have to take it back to the library... this time we will read it!
And this is a lovely vintage book that is available for free on google books, as a pdf, for a Kindle, etc. I think Cassia especially will enjoy this one!