Teacher: “If I gave you 2 cats and another 2 cats and another 2, how many would you have?”

Johnny: “Seven.”

Teacher: “No, listen carefully… If I gave you two cats, and another two cats and another two, how many would you have?”

Johnny: “Seven.”

Teacher: “Let me put it to you differently. If I gave you two apples, and another two apples and another two, how many would you have?”

Johnny: “Six.”

Teacher: “Good. Now if I gave you two cats, and another two cats and another two, how many would you have?”

Johnny: “Seven!”

Teacher: “Johnny, wherein the heck do you get seven from?!”

Johnny: “Because I’ve already got a cat!”