    Senterice-t: These underbo.a hatuial colrse.of developrint through  ireét ‘cattact.\wth the environment. daring the fist two, years of ie    simiais tothe process ghexploretion.and, disceyery described -by  Piaget         Sentence\-2: These ‘go-tyovght"s’ cpuse.-of-developrnent whicis  produces the smartest children,