something you might be interested in for science:
www.livinglearningbooks.com It is a guide that gives you TONS of resources for different studies. We have 2 years worth here, and they are wonderful.

You might find something there that interests your ds - and it will take the work out of finding appropriate books. We have used the Earth and Space science guides. We also have the one on animals, plants and humans.
You might also want to just get a couple of good Usborne books to use as a guide. We used Encyclopedia of World Geography along with Story of the World for our history for a couple of years. We also used a couple of the science books and did notebook pages.
For history, many of us are using or have used Story of the World as a basic guide. Pick a time period you might find interesting. The main book is simply stories about the time period. Then you can use those as a jumping point to get more books form the library. The activity guides have reading suggestions in them. They offer read aloud suggestions as well as books that younger children can read on their own.
Another place I have used when not using their curriculum (I'm using the curriculum now because I am worn out for piece mealing for now), is
www.sonlight.com The booklists are really good guides for what would be age/grade appropriate.
HTH