Earlier quoted context omitted.
" after grade 8 " (the OPs concern) is more like 15 y.o., right?
Even at 15 years old you’re still a long way away from having a fully developed pre-frontal cortex. We used to think kids were like little adults, then we learned a bit about how the brain develops and how wildly wrong that mental model was.
While teenagers are not fully adult in some ways, they are also very different from a 12 year old.