Forty years ago we learned fractions with chocolate bars. A trustworthy child would be chosen to walk from the primary school to the local store (about 5 minutes walk for an adult, probably about two minutes for a child who was just given money by a responsible adult to buy chocolate) and bring back some chocolate, and then kids who raise their hand and give the correct answer to fraction questions get the fraction in its physical form as chocolate. What's half of this third of the bar? A sixth, and now because I knew that I get to eat 1/6 of a bar of chocolate, whereas the kid who enthusiastically answered that it's a quarter does not because that's wrong.