    Sentence 1: Vygotsky's. theory has  Ibeen the wellspring of our recent  lJappreciation of the profoundly social  Inature.of even very young children's  imaginative play'and its  wide-|  ranging infiuence on cognitive anel|  social development.    sentence 2: Vygotsiry's theory has  been affirmed a number of times in|  lour observations.         