Riordon and I were discussing commutativity.
Me: So is subtraction commutative? What's ten take away zero?
Me: And zero take away ten?
Rio: Well, you can't.
Me: You can't‽
Rio: Well, my teacher said you can't.
Me: She did?
Rio: Yes, I said you could because of negative numbers and the teacher said we didn't do those for a couple of grades yet.
(I remember the same thing happening to me when I tried to use division in infant school.) The daft thing is that Rio is quite capable of working in the complex plane. I wonder how I can teach her not to let the school put brakes on her exploration. It bothers me firstly that she'd understood what the teacher said to mean that she should pretend negative numbers didn't exist, and secondly that she then took this to apply to every situation in her life (not just as needed to get by in school maths classes).