Two days ago, I and my 4-year-old son were having a great time together when he suddenly asked: “Daddy, what is zero?” Right in the middle of heavy physical play activity, I took a deep breath, and started to think about how I can describe the number zero to my son. The conversation went like the following:

– OK, look around you, how many airplanes are there in this bedroom?
– None.
– Exactly. So, there are ZERO airplanes.
– Zero!
– Yes, zero. Hmm, another example: how many beds are there in this bedroom?
– One! One bed!
– Yes dear. There’s only one bed, you know what one is. How many dinosaurs are there here?
– Twenty!
– In this room?
– No, in the other one.
– So, in this room, there are …
– ZERO! Zero dinosaurs in this room!
– Perfect.

Having described the concept of zero to my son, I felt like a proud father. Then we got ready to go out. I helped him to get dressed, then we left our flat, and started to wait for the elevator. When the elevator arrived, I’ve opened the door, so that my son could step in. I knew he likes to press the buttons in the elevator, so I let him do that as usual. Since we were to leave the apartment, he knew he had to press the green button that has the number zero on it. He looked at me, smiled, and said “zero floors daddy!”

“How many floors are there at the entrance?” I said to myself, and then started to think whether it is possible to describe this meaning of zero to a 4-year-old. I still don’t know how to do it: creating an association between “none” and “zero” was easy, but describing zero as the starting point seems more tricky. As if this is not enough, our elevator has also a “-1” button!

Maybe I should go back to my notes on “How to Learn Math”:

Do you have a better idea? Feel free to share your creative ideas on different ways of describing the concept of zero to a 4-year-old.