I read Valley of the Horses too - - weren't there three? I'm not
  sure if I read them all. I loved the hard science of it: I was
  always a fan of hard science fiction, although I didn't know it
  was called that at the time. I loved that I'd be reading it,
  recognize a fact that I knew was true, and then I'd end up
  learning a lot of stuff I *didn't* know, but I could trust the
  author. The one teacher definitely read it (we'd discuss stories
  from it after school) - and the other teacher? I don't know. I
  suspect she did too, but I think for her it was a guilty
  pleasure. == "prehistoric romance". Sometimes it's categorized
  as that. == Yeah - I think it's the best way to learn history -
  if they do it right. A few hours ago, I had to help my nephew
  through some American Revolution homework. 5th grade. They're
  going over Boston Massacre. Common Core teaching materials. The
  way they teach it now in 2016? The way I was taught it way back
  when? Not much different. Dry with purposely confusing
  questions. One of them had me stumped, but I refused to look on
  the Internet for the answer - he didn't either because he was up
  for the challenge. finally it hit me and when I said it, he got
  it too... and then I was pissed because it's a question that no
  5th grader could POSSIBLY answer on their own. ugh. Sorry for
  the side-track - just a contrast to "good ways to learn history"
  and "crappy ways to learn history" ==