When I was a child, probably between the ages of 6 to 8, I liked to make model gliders from balsa wood. My father taught me how to cut the balsa wings and fuselage from a plywood template. Once he's seen me do it a couple of times, away I went with the Stanley knife (not sure what else they're called in other parts of the world. Retractable utility knife perhaps) and was making my own gliders. Not sure why, but this day I happened to be kneeling, rather than working at the bench. Sure enough, the knife slipped and embedded itself in my thigh. Three stitches later, I had learned to be really careful with sharp knives and how to cut things more safely.
I've driven a chisel into my finger while trying to finish a mortise and tenon joint. Use a vice, not your hand, to hold the wood. Came close to ripping out an artery while climbing an aluminium fence, just ended up with a nasty scar on the side of my wrist. I took much more care climbing fences after that. Barbed wire fence scars across my legs though. Can't even remember how that happened.
Anyway, kids do stuff and hopefully they learn without killing themselves. A few cuts, scratches, a bit of blood and some stitches seems like par for the course.