I DO have common sense and I guess I am of the teach to use properly with supervision and definite direction. If they aren't taught how will they learn whether 5,8 13, 15 or older? They will more than likely "sneak and do". But,on the same note I am all for "kept up" and out of "reach" and "view" "ask" when need/want to use. Quite often when kids see adults doing, they "do" because they are curious and want to try the "fun" thing and don't get that opportunity.
For instance I have two -13 year olds, their dad welds for a living. This past summer they asked to learn how to weld, they both know how now. In fact one with "dads assistance" is building a go-cart, they have it almost done except a motor, clutch and brakes.But they both also know that this is a "supervised only" thing. And yes, they do know how and do use my rotary cutter knowing they but must have no distractions (but most times they usually just ask me to do it for them.)
I do not mean this to be snidely or rude or anything of the sort so please don't take it that way,it is just "My opinion" and how it is with us.