Many of the already mentionned books. Hal Clement's Mission of Gravity, in the hard science genre. As a kid I was absolutely stunned by The Tripods. I highly r

Many of the already mentionned books. Hal Clement's Mission of Gravity, in the hard science genre. As a kid I was absolutely stunned by The Tripods. I highly recommend these books (trilogy) for your kids (10-13 yo).