A piece-of-scrap. That’s how the townsfolk on Trinket’s planet label her. The twelve-year-old is determined to prove that she’s more than just a discarded android, but her prosthetic leg and blue veins in her hands make her wonder about her true identity. Trinket knows that she must get off-world before the cruel and powerful Remnants send her to the scrap yard, but things take a turn for the worse when the Remnant Supreme Leader discovers her existence. Trinket could be the key to a lost spaceship that is rumored to hold the greatest hoard of gems in the galaxy, and the Supreme Leader wants it. To uncover the truth about her identity, Trinket must confront the evil Supreme Leader or get to the treasure first. But what if the truth is too shocking to bear? Award-winning author Rae Knightly presents EXOSTAR, Book 1 in The Lost Space Treasure Series, which thrusts a young girl into a universe full of alien civilizations and an epic hunt to uncover the greatest treasure of all. This witty upper middle-grade science fiction story with a cast of unforgettable characters is perfect for the space explorers of tomorrow and fans of Alita, The Prometheus Project, Hana Hsu, and Dragon Pearl.
Middle grade science fiction, or sci-fi as it’s called, is an electric genre that often combines mystery, action, and adventure. As someone who tends to enjoy books featuring strong female protagonists, this is one genre that sure features a lot of boys! Still, it’s fun to see that more and more girls are gracing the covers of these stories. For this list, I’ve stuck to the classic definition of sci-fi, especially in terms of “relating to science” and being “futuristic.” I’m sure sci-fi nerds will tell you that there aren’t many hard sci-fi stories here, but these are my favorites. If you like books with plenty of action and adventure against the background of solid science, you’ll love these books.
🔎 If you’d like to learn more about the content of a book, you can read my full review or use one of the other three methods I recommend in this post about screening a book’s content.

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15 Thrilling Middle Grade Science Fiction Books
Here are 15 of my favorite middle grade science fiction books:
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What a great list! Do you know of more “science-y” school books like the B.E.S.T. series or Explorer Academy books? There are so many magic school books, but it feels like sci-fi is lacking in that regard.
Ahh nothing comes to mind right now but I’ll be sure to send any recs I find your way.