This seems to be the place for this...
Mum was visiting my sister and nephews this weekend. One day, they were at the library, and there was little history display, with an old school desk and an abacus. Oli (6) asked what it was, and Mum explained, and then things moved on to Roman Numerals, which she explained to him back at home - how they worked, and how it was hard to do sums, on account of not having a zero and so on.
Next day, they went out to meet a friend of Mum's for tea. This friend isn't very good at talking to children, so Oli got a bit bored. Quietly, he got out a notebook and pencil he'd been bought, and starting writing. After a while, curious about what was keeping him so occupied, Mum took a look. He was writing out sums for himself. In Roman numerals.
Now she's worried he'll go back to school and demand to be taught in Roman! He's already been moved up a year in maths apparently.
I'm wondering whether to bring up binary when we go down there next week....