I'm not sure if this is going to be the best place to look for both 'nothing unfit for children' and 'not too much reading' to be honest. You might browse the Edutainment section, and if you get the site extension from BD's profile
here, you can search by the Geared for Children tag.
But it's not a popular category, most of the users on this site are teenagers and more interested in edgy fantasy epics. I guess I would say that a kid that isn't comfortable reading stuff at a maturity level like the Hunger Games may not find a whole lot to choose from here, but maybe someone else can suggest a couple of specific stories. (It's really too bad the author of the Princess Pretty series took them all down...)
e: Maybe the
Carmen Sandiego story?
Or
Inepta Academy?
Hmm...
One Tiny But Mighty Pilchangk Adventure?
I'm not really sure what constitutes 'too much reading'.