Potpourri, are you using the “classic” series for Elemental Science? They have a number of lines, I see.
For the OP, I actually just bought some of RS4K at a homeschool conference. I was thinking of my 3rd grader who has more interest in science, but not a big fan of nature (gets freaked out by bugs after some unpleasant close encounters). After talking with the author at the conference and looking through her books, I felt like physics and astronomy would be good for her, but thinking of the younger kids thought they might have some interest in the bio and chem. And I have to say that I really liked they way some of the topics were described in those.
Bottom line is that I ended up buying all 4 sets of the elementary level (didn’t buy the geology…yet). lol I’m not a big “experiements” person, so we shall see how that end goes. But the books look interesting. I can post more in the weeks ahead as the kids start using them.