The best, no the only thing we can do for our children to keep them safe - is to educate them as best we can. Kids are not stupid, but they are often ignorant of the risks involved and unable to consider the consequences of risky behavior. Many of us survived learning to ride the street on our own without dirt experience and without any real training. It's the school of hard knocks to be sure, the test often happening before the lesson.
My youngest son (25) doesn't know how to ride a motorcycle. I may pick-up a small dual-sport to teach him so that he is prepare when and if his son asks to try riding. I'm ready to buy a Z50 for the grandson but he's only 2 months old so I may wait just a little bit more. ;-)