If your kids are anything like my JHS kids, it's going to be hard to find any "book" they can read that isn't like "Baby's First Reader" or whatever. Things written for their level will be well below the appropriate age-interest level.
The only thing I can think is that graphic novels or comics might be a good compromise. Besides the fact that kids here love graphic novels already, it would help them have illustrations to give some context and make it easier to understand what they're reading. There are lots of publishers that take well-known Western classics, abridge them, and put them in comic form. That's how I read a lot of H. G. Wells and Jules Verne when I was a little kid. You could look into something like that...