When I was younger, I was trying to cut some french bread that was pretty hard. I held it in my left hand and took the knife and sliced downwards towards my hand, I didn't want to have to wipe off the crumbs. Of course, big ole' gash when the knife finally made it through the tough bread. The next day, a friend asked what had happened, and said, "Didn't you ever learn to cut bread??"

It's always those little obvious things that you think don't need to be taught that little kids will always mess up horrifically. Moral of the story, don't assume kids have much common sense.