I'm going to establish pseudonyms for my kids for the blog, but both their names start with G and I don't want to call one of them little sister or big brother or something like that. So they are both going to be **G** -- G1 for the big brother, who is currently 4 years old (almost 5!), and G2 for little sister, who is currently 1 (almost 2!). So G1.4 means my son at age 4, G2.1 means my daughter at age 1.

This week is my spring break and we were letting my wife sleep in this morning, so the kids and I were playing together in the kitchen. They were both slipping underneath my legs to pop up on my opposite side while I cried "How did you get over *there*? You were on my left a second ago!!"

G1.4 suddenly announced, "When I'm 100, G2 will not even be ... 60 yet!!"

I said, "That's interesting -- you *are* so much older than her. How did you figure that out?"

G1.4: Well, I'm much older than her, and I will always be older than her

Me: That's definitely true, you will always be older than her - but I'm curious how you figured out 60 for when you are 100.

G1.4: I don't know!

Me: Well do you want to figure it out? How old are you know? And how old is G2?

G1.4: She's1. And I'm4. [emphatically]

Me: And how old will you benext?

G1.4: 5!! And G2 will be 2!! So when I am10, she will be5!

Me: Huh -- I didn't quite understand that one. You're totally right that she will be 2 on her next birthday, when you are 5. Can you explain how you got 5 when you are 10?

G1.4: When I am 5, 6, 7, G2 will be ... 2, 3, 4.

Me: I love that -- that's really clever! I like how you counted up your age and her age together. Can you do that again to figure out the other question? ... About how old she will be when you are 10?

G1.4: [long pause] 8, 9, 10, and she will be 5, 6, 7. G2 will be 7!

Me: Awesome! High five! So, how old will she be when you are 100?

G1.4: [smiles] She will be just a littttllle bit less [holds thumb and index finger about half an inch apart] actually, areallylitttttllllleee bit less [holds thumb and index finger a couple of millimeters apart]

Me: Ha! I love that! Nice figuring!

**Questions:**

- How
*did*he get the first estimate of 60 for G2's age? [My guess: "60-100" is his current "big number". As in, "I am 60-100 tall! I can count to 60-100!"] - Where did 5 come from for his initial estimate of her age when he is 10? [My guess: 5 was the last number he had said for himself, for his next birthday, so it was the number on the tip of his tongue]
- I didn't suggest the counting up method directly, though it seems like a natural way forward from my suggestion to think about his and her next birthdays, but the counting in threes was totally him. Why threes?
- Did he really have a changed sense of the relative difference in ages after our discussion? He started with a brag that he would always be
*much*older than her, and maybe thought that he would get*more older*[sic] over time. But at the end the "really little bit less" suggests a recognition that the difference would not be very big. He wasn't up to counting up all the way to 100 (he can do 50 comfortably right now, and has gone all the way to 100, but he gets confused toward the end) so I didn't push any further, and so I don't know if he recognized that the difference in ages would always be three. Conveniently, their birthdays are two weeks apart, so we can ignore the brief interludes when his age is only two more than her's.