We should teach them at the second stage because at that stage they can buy chocolates snacks and even rum errands, to make them understand that there is a digital currency known as bitcoin,this will help them know quick about bitcoin in other to join the moving train when it is the  right time for them. I heard a boy of 15 that his father has 7 btc and the boy was the next of kin to these bitcoin. Lack of proper knowledge on btc made him gave out one btc to someone.