This happened on Monday.
Monday was my brother’s birthday. He turned 22. When I got to school in the wee hours of the morning, I drew a birthday cake on the board next to the date and labelled it 11000.
As you can see, I typically make the date a puzzle or a problem to solve. Sometimes it’s math the students know, sometimes it’s not. Sometimes they ask about it, sometimes they don’t. 11000 isn’t anything that I’ve taught in class, but I thought they might ask about it.
No one in Calculus asks, or in first period precal. But in third period, Advanced Precal, they notice the birthday cake.
Student: “Who turned eleven hundred today?”
Me: “It’s not eleven hundred, it’s twenty-two.”
I just smile and keep walking around, letting them work on their warmup. If they were interested, they’d think about it and keep asking after the warmup. If not, they’d let it go. I wasn’t going to force it.
Eventually, a student raises her hand. This student is very tentative and doesn’t always believe in herself, but she’s almost always right. She’s also extremely sweet. “Are you sure it’s twenty-two? It’s not twenty-four?” she asks.
I look back at the board. “Oops. Yes. Thanks. It should be…”
“10110, I think,” my student finishes for me.
So, while I’m not thrilled that I can’t add 8 and 16 correctly, I was thrilled that a student figured out that it was binary, figured out I’d made a mistake, and had enough confidence in herself that she would point out my error.
Oh, and my younger brother is a computer scientist. Thus, binary.