Flea reminids me of how my mother taught my brother and I to add. We took the train to Gramma's house in Seattle when we were oh, about 6 and 8? Which was fun! On the way home, Mom picked up some souvenir Amtrak playing cards in the lounge car and proceeded to teach us to play Blackjack. This was amusing to the couple of businessmen in the car, but a pair of matronly dowagers became quite flustered. After several dirty looks and comments to the effect of "do you really think you should be teaching your kids to gamble?" failed to shame Mom into subservience, I seem to recall their reporting her negligent behavior to a conductor. Who of course said that since no money was changing hands, there was nothing he could do about it.
What can I say? I was a quick learner. When we got back to school I could count to 21 faster than anyone else in my class and got high marks in Math. Too bad Hoyle hasn't developed a game of chance yet that involves long division. My brother could have really used it.