I was playing SET with my family (the object of the game is to get 3 cards for a set and the person with the most cards at the end win)
At the end of the game, we counted our cards and I said to one person “you have miscounted” They looked puzzled but checked and was surprised to learn that I was correct. I thought it would make an interesting question in class. I changed the original numbers. I then thought it might make a good starting point for a discussion on divisibility of 3. I then started thinking of other questions that relied on the divisibility of 3.