I would talk to the trip leader, who should be carrying a means of emergency communication for the group. I frankly would not entrust a youngster with a PLB of SPOT; consequences of "pushing the button" when it's not an emergency could be dire.

I'd be more concerned about knowing the safety rules for the group and the qualifications of the adult leader--again, contact the trip leader.

Hopefully there will be several adults with the group and the group will be within the legal wilderness group size limits (usually 12).
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey