## November 22, 2014

### Age vs. Birth Year (#tmwyk)

Last night I was talking to my 13 year old foster daughter (she's been here for over 3 months! hard to believe!) and the conversation wound around to my college 80's themed dodgeball competition, which somehow transitioned to J asking what year her friend Katie was born if Katie is 30 now.

You can figure that out.
J: I don't know
Well, how old was she in 2004?
J looks at me like this is an equally difficult question and she has no idea why I asked it.
It's 2014 now, how old was she in 2004?
J: Oh. She was... 20.
Okay, so how old was she in 1994?
J: She was 10... So she was born in 1984!

Conversations about the 80's continue. Then J asks what year I was born (I'm 29), then answers her own question - 1983! I shake my head, "I'm one year younger than Katie." J realizes that I was born in 1985, and proceeds to share her thought process (which I don't remember word for word but I love that she already knows we're going to have this conversation and wants to share). We discuss how it seems like one year younger should mean subtract one from the birth year, but it actually means I was born one year more recently.

Then J turns the conversation to how old she will be in the future.

J: How old will I be in 2025?
You can figure that out.
J (pulls out a chair and sits): Let me think about this... In 2015 I'll be 14.
(Mentally I'm super excited that she's about to use the count by decades strategy I walked her through earlier)
J: In 2016 I'll be 15.
(Mentally I'm sad she didn't use the strategy but interested to see if she'll count all the way there. And keeping my mouth shut with a neutral/interested expression on my face.)
J: In 2017 I'll be 16.
(Her face lights up and I realize the alternate strategy at the same time she does.)
J: So in 2025 I'll be 24!
What did you just realize?
J: Since I was born in 2001 I can find my age by subtracting one from the year! So if I forget how old I am I can always ask someone what year it is.
People might think you have a concussion if you don't know what year it is.
J: Well if I forget what year it is I can always ask myself, "How old are you, J?" (we laugh because she asks this very expressively, sometimes 13 is a really fun age) ... In class today they were asking us about what life would be like in 2050. So I was wondering how old I would be and I figured out that subtract one thing.

So then she wanted to know what year it would be when she turned 99. My first thought was year 3000, but as I was thinking that she was saying 99+1=100 so I realized that it would be 2100, not 3000. While I was realizing how much more sense that made, J was saying how it wouldn't really be 100, it would be 3000. I should have asked her how she got that, but I was doing too much thinking of my own so instead I went with, "You were born in 2001, how long from then is 3000?" She realized her mistake and then I shared that I'd done the same thing!

Conversation turns to getting old and how long she wants to live and me telling her that 70 is not old enough to plan on being done living. I told her that the average lifespan is in the 70's and that average means middle - so lots of people live longer than that. That factoid didn't lead to her doing any more math, which was just fine with me.