I would be really hesitant to loan any gear to somebody I didn't already know on a personal level, i.e. we hang out at eachothers houses from time to time.
If you're fortunate enough to have "extra" equipment like an old amp or another bass that you don't mind losing, then go right ahead. I've helped out some highschool kids before and it was quite rewarding to see them shine, plus I got to hear my gear from the audience perspective which was nice.
I would write up some form of contract for them to sign, and don't be shy about it as you are doing THEM
a favor. Take a deposit of some sort, or at least document the "what happens if..." clause. If they're legaly minors, get mom or dad to sign it as this needs to be fully legal in order to CYA.
The more you plan ahead the less
will be in your future.