Welcome!
What's the age range on these kids?
We do have a new "family friendly" category but the quality is a little spotty right now, although we're hoping to expand it as people find the time to write more. We do have teachers bring their classes by pretty often, but they're typically more interested in having the kids practice writing their own games.
If these are older kids I'd suggest
Dreamtruder just off the top of my head, which reads a lot like a YA novel.
Or something from the
Homo Perfect us series which at a time was wildly popular with younger site members.
But even with games that are fine as far as content goes, they may be a little verbose for reading outloud.
I guess I might as well mention also that's there's a pretty extensive sci fi text game I started playing through for the forum
(here) recently, it might actually be ideal for something like this. (And can be made available as an .exe if you don't want to mess around with installing the program needed to run it. )