If I give you two rabbits and two rabbits and another two rabbits, how many rabbits have you got?

Teacher: Johnny.  If I give you two rabbits and two rabbits and another two rabbits, how many rabbits have you got?
Little Johnny: Seven!
Teacher: No, listen carefully again. If I give you two rabbits and two rabbits and another two rabbits, how many rabbits have you got?
Little Johnny: Seven!
Teacher: (Sigh) Let's try this another way. If I give you two apples and two apples and another two apples, how many apples have you got?
Little Johnny: Six.
Teacher: Good. Now if I give you two rabbits and two rabbits and another two rabbits, how many rabbits have you got?
Little Johnny: Seven!
Teacher: How on earth do you work out that three lots of two rabbits is seven?
Little Johnny: I've already got a rabbit!