Teacher: “If I gave you 2 cats, another 2 cats, and another 2, how many would you have?”
Johnny: “Seven.”
Teacher: “No, listen carefully… If I gave you two cats, another two cats, and another two, how many would you have?”
Johnny: “Seven.”
Teacher: “Let me put it differently. If I gave you two apples, another two apples, and another two, how many would you have?”
Johnny: “Six.”
Teacher: “Good. Now, if I gave you two cats, another two cats, and another two, how many would you have?”
Johnny: “Seven!”
Teacher: “Johnny, where do you get seven from?!”
Johnny: “Because I’ve already got a cat!”