The teacher was asking the kids some simple arithmetic.

The teacher asked Tommy "If I give you two rabbits and then I give you another two rabbits, how many rabbits do you have?"

Tommy answered: "Five."

Teacher: "No, listen carefully again. If I give you two rabbits and then I give you another two rabbits, how many rabbits have you got?"

Tommy said: "Five."

The teacher was exasperated: "Let's try this another way. If I give you two bottles of pop and then I give you another two bottles of pop, how many bottles of pop have you got?"

Tommy: "Four."

The teacher was pleased: "Good! Now we're getting somewhere, if I give you two rabbits and then I give you another two rabbits, how many rabbits have you got?"

Tommy: "Five".

Totally flummoxed, the teacher asked: "How on earth do you work out that two lots of two rabbits is five?"

Tommy said: "I've already got one rabbit at home!"