You don't know many children then - I have personally endangered mine and that of friends while I was around 10-12. The most telling example - a close friend (we were both 12) wanted me to attack him with knife to show me how to block. It was pure luck I tried to stab him at much slower speed than I was able so the whole story ended with his very deeply cut palm instead of blade in the guts.

Children are not stupid but they have some very vague concepts of what is safe.