> students who tended to speak more ended up doing _worse_ on final exams.
It is possible that this simply tells us that the final exam was only or primarily a written one. I know it is not directly comparable but my children learnt Norwegian starting at age 3 1/2 (after they already spoke English) without any formal instruction at all, just by speaking with other children and the staff at the kindergarten.
It is possible that this simply tells us that the final exam was only or primarily a written one. I know it is not directly comparable but my children learnt Norwegian starting at age 3 1/2 (after they already spoke English) without any formal instruction at all, just by speaking with other children and the staff at the kindergarten.