Welcome to the forum Ash..... Great to see your son shows an interest in both the outdoors and rocks/minerals. Looks like a young prospector in the making. Some supervised time reading the forum threads and watching some members vids (especially some by Balx) can show him the fun kids can have on a stream prospecting.
If he has a genuine interest, encouragement in this hobby could lead to an academic interest in Geology down the track, and at very least an understanding of how the environment and nature plays a big role in gaining self confidence while out in the elements.
If you have any questions, no matter how irrelevant you think they may be, just throw them at the members and they will steer you both in what I'm sure will be the right direction.
All the very best with it,
Cheers Wal.