Young relative must read:
The Star Beast
Red Planet
Tunnel in the Sky
Rocket Ship Galileo
Have Space Suit - Will Travel
The Rolling Stones
These were originally serialized in Boy's Life in the 50's (IIRC). All good books reflecting self/family-reliance and good civic values.
Star Trek's Trouble With Tribbles episode was a blatant rip-off of a sequence involving "flat cats" in The Rolling Stones, also IIRC.
David Gerrold discusses in his book about the creation of that episode. He admits with some chagrin that the whole "fluffy critters who eat many times their own weight" concept had to have been inspired by "flat cats" (he's a Heinlein fan), but states that he didn't consciously rip them off. Frankly, he did such a nice job on the episode as a whole that I'm willing to give him the benefit of the doubt.