I started running a saw under supervision when I was probably 10-11 years old. I had my own saws by the time I was 13-14. The idea of PPE was unknown then.
If you elect to set junior up with a saw he can run under supervision, here's my 2c:
1. PPE. Period. It will be expensive for a kid who is fast growing, but so what?
2. Small engine saw with SHORT bar. Seriously short bar. I started out with a 10" bar on a little Homelite, and the short bar kept me from cutting the ground, myself, etc., and helped develop good cutting technique. It also (somewhat) reduces the need for steel toe boots, which may be a hard-to-find item for kids (don't have kids myself, but I'd guess they're a rarity in children's sizes).
3. Consider a slower-revving reed valve saw such as the rear-handle Echo 3000 series. The slower saws actually help with learning - cutting technique, how wood hinges and binds, how chips discharge (or don't) from the cut - and I think that this will pay off later on. They also tend to kick back less and pose less risk of harm to the operator.
4. Teach proper sharpening technique. If you're gonna run the saw, you're gonna care for the saw. Period.
5. Lots of how-to learning on YouTube. Husqvarna has a good series of saw techinque videos - maintenance, felling, bucking, limbing - that should be requisite viewing for any new saw operator.
6. Empower the young person to feel comfortable critiquing/correcting your cutting for both technique and safety issues, just as you will be critiquing/correcting his cutting. This will make both of you better and safer cutters.
