Gradually, the child takes increasing responsibility for attaining intersubjectivity, until both parties make similar contributions to the shared mental state that fuels children's learning in the  zone. 
( Gradually ( , ( ( the child ) ( ( ( ( takes ( ( increasing responsibility ) ( for ( attaining intersubjectivity ) ) ) ) , ) ( until ( ( both parties ) ( ( ( make ( similar contributions ) ) ( to ( the ( shared ( mental state ) ) ) ) ) ( that ( ( fuels children ) ( 's ( learning ( in ( the zone ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB Gradually)) (, ,) (NP (DT the) (NN child)) (VP (VBZ takes) (NP (NP (VBG increasing) (NN responsibility)) (PP (IN for) (S (VP (VBG attaining) (ADVP (RB intersubjectivity)))))) (, ,) (SBAR (IN until) (S (NP (DT both) (NNS parties)) (VP (VBP make) (NP (JJ similar) (NNS contributions)) (PP (TO to) (NP (DT the) (JJ shared) (JJ mental) (NN state))) (SBAR (IN that) (S (NP (NNS fuels) (NNS children)) (VP (VBZ 's) (VP (VBG learning) (PP (IN in) (NP (DT the) (NN zone))))))))))) (. .)))
The child is never expected to take on more responsibility.
( ( The child ) ( ( ( is never ) ( expected ( to ( ( take on ) ( more responsibility ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN child)) (VP (VBZ is) (ADVP (RB never)) (VP (VBN expected) (S (VP (TO to) (VP (VB take) (PRT (RP on)) (NP (JJR more) (NN responsibility))))))) (. .)))