I think the best way to approach such an endeavor might be to essentially demonstrate Clarke's Third Law in each story. "Any sufficiently advanced technology is

I think the best way to approach such an endeavor might be to essentially demonstrate Clarke's Third Law in each story. "Any sufficiently advanced technology is indistinguishable from magic." So what you could have is essentially a bunch of stories where characters discover things that seem magical, but end up having very rational explanations (much like Federation tech in the world of Star Trek was pure magic to the less-advanced civilizations they encountered). Maybe even delve eventually into designing experiments to prove assumptions about the principles being discovered, etc, and explaining the scientific method. It would be a great way to encourage critical thinking in kids without crossing into too fantastical a world for there to be logical explanations for some things. Even with Star Trek, where some things are potentially nonviable (transporters, for example), they still had logical explanations that make sense at a high level.