Since the girls aren't interested in a school lesson at home, the books we look at are simple and full of images. If I've done my homework, I'll have learned a few facts and casually bring them up.
Here are a few books that retained the girls' interest (read: colorful, few words), despite being too young for Pea (13 years old):
Let's Visit Greece (Around the World) by Susie Brooks
Again, it is a little juvenile. It has a simple, fun format with basic information for preliminary look at Greece with kids. It also mentions what one would need when visiting Greece, which is fun to imagine :) The girls and I like the basic Greek words it explores, with pronunciations.
Greece (We're From . . .) by Victoria Parker
For kids aged 6-8, this book introduces us to kids growing up in Greece, and their lifestyles. The girls' were appalled to read about 3 hours of homework each night! Photographs are washed out, but reading about other children never fails.
Books are a wonderful way to experience new worlds and ideas. Our house is filled with books, most of which are borrowed from our public library. Public libraries are an incredible resource, making books accessible to everyone, and we highly encourage everyone to discover theirs. If you are hoping to build your own home library, I've made it easy by including a link in the book title linked to Amazon.com. Please note that I have become affiliated with them, and would receive a small commission.