The other day I was at my Japanese in-laws house and their two grandchildren, a girl of 10 and a boy of 6, were playing. The girl suggested going to the park and the boy replied that it sounded like a good idea. In Japanese, to say something ‘sounds good’ or ‘ seems hot’, etc. there is a special grammatical construction for adjectives. Most adjectives end in -i. Cold is samu-i. Good is yo-i. To change to an attribute Process you drop the -i and add -sou. Thus, samu-i becomes samu-sou (it seems cold ). It is a very regular rule, with one main exception: to inflect yo-i (good) you have to add yo-sasou. While they were playing, my Japanese nephew forgot this rule and produced *yo-sou (a common error also of Japanese as a Foreign Language learners, including myself). Immediately, his older sister corrected him. Whereupon he again produced the non-standard form. Again his sister corrected him, this time in a stronger tone of voice, and finally he produced the standard form. And then they went to the park.
Another, similar, example occurred in one of my group classes with a (Japanese) past-tense inflection that was overtly corrected. What was particularly interesting in both cases was that it was the older sister who did the correcting. In the group class there were 6 other children yet only the older sister felt able to give correction. Language as socio-cultural scaffolding.