These are the One Small Square books that are used in Bigger and Preparing: Seashore, Woods, Arctic, ,Cactus Desert, and Coral Reef. One Small Square Backyard is used as a DITHOR choice in level 2 and Tropical Rain Forest in level 3. There aren't any scheduled in the upper level programs now and I don't think they'll be something she adds to the future guides. That's just my guess but I think the science in the upper guides will require something more, so I think you would be fine to use any of the other One Small Square books. I see Pond, the Night Sky, African Savannah, Swamp, and Cave as other One Small Square books. The only thing to be careful of is I'm not for sure if these are written from a Christian perspective so you might have to watch out for evolutionary content.
Another series that is great to read about science is the Christian Liberty Nature Readers. They have them starting from grade K up to grade 5. The 1st grade one is scheduled in the emerging readers but you could probably read the K one and second grade one without any conflict. They have lots of interesting things in there about the nature around us.
Another thought is a few of the science readers from Rod and Staff. When I was at the convention this year I saw some readers they had on NC in the fall and winter and NC in the spring and summer. I picked them up because we live in NC and I thought it would be great to read these along with some nature walks. I think they have others that fall in the category of science readers.
One last thought is just check out some books at the library. I think the idea of a living book is one that was written by a single author who was very passionate about his subject. I'm sure there is more to it than that, but that is a starting point. So look for books that are written by one author and written in a more conversational or story form versus a textbook form. I'm sure you can find a a lot of fun books about topics that your ds enjoys.
