The same thing happened with my son when he was 4, the first and last year we had him in school. "But Mom, she's a *professional* teacher. It's her job to know what to teach children, and she must think that this is the right work for me. So I must be stupid, because you'd have to be stupid to have to practice this stuff."
Oh! When I think of readiness to learn level, I think of ranges. After all material can be 'too challenging' ' hard but possible' 'hard sometimes' 'easy but fun' - for my son, I articulated a level that is 'Shaming' - exactly what you son described. So far below readiness to learn level that it shames the learner.
It took a while for me as an adult female to understand that for some young males, there is a thing called 'Shame' - feeling bad for how I appear to others. I was fortunately listening to lectures about 'The Odyssey' by Homer at the time, and it went into great detail that 'standing in the eyes of the others' was directly translated into the internal state of the self. I was more of a 'I'd rather have a whole pumpkin to myself than have a teeny share of a grand chair' kind of kid. (I saw a poster of this in 7th grade English class and can remember being surprised by how well it described me.)
Hugs
Grinity
