Andrew recently started doing some first grade school at home. He's doing some reading lessons and math lessons during the week. This week I introduced the idea of the 'empty set' or zero.
So I showed him the little card with nothing on it. And told him it was an empty set. Then, I asked him to tell me how many black birds were in the room. The conversation went a little something like this . . .
Me: "How many black birds are in the room?"
Andrew: "Four."
Me: "What? No, really, how many black birds are here in this room? Real ones."
Andrew: "One."
Me: "No, Andrew. There aren't any real black birds in the room. We're not talking about pretend ones. You're supposed to say 'none'. It's an empty set. Get it?"
Andrew: "Yes."
Me: "Say 'yes' if I tell you an empty set and 'no' if it's not an empty set."
Andrew: "Okay."
Me: "How many Daddies are in the room? Is it an empty set?"
Andrew: "Yes." - because Daddy was at work.
Me: "How many tables are in the room? Is it an empty set?"
Andrew: "No." Because there is one table in the room. (I think he's getting it now.)
Me: "How many lasagna's are in the room? Is it an empty set?"
Andrew: "No."
Me: "It IS an empty set because there are no lasagna's in the room."
(not sure if he's getting it after all)
Me: "Andrew, what is an empty set?"
Andrew: "Spaghetti?"