There are three kinds of people: Those who get math, and those who don't.

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, where in the heck do you get seven from?!"
Johnny: "Because I've already got a cat!"