9 4 5 , ▁K rug ▁became ▁the ▁Wisconsin ▁State ▁C urr icul um ▁Co ordin ator ▁and ▁held ▁a ▁concurrent ▁position ▁as ▁Associ ate ▁Professor ▁of ▁Education ▁at ▁the ▁University ▁of ▁Wisconsin – Mad ison . ▁ ▁In ▁ 1 9 4 7 , ▁he ▁returned ▁to ▁Stan ford ▁as ▁an ▁associate ▁professor , ▁but ▁returned ▁to ▁Mad ison ▁the ▁next ▁year . ▁ ▁K rug ' s ▁early ▁works ▁de alt ▁with ▁US ▁social ▁life . ▁Begin ning ▁in ▁ 1 9 5 0 , ▁K rug ▁began ▁a ▁long ▁publishing ▁career ▁on ▁the ▁history ▁of ▁US ▁education . ▁ ▁In ▁ 1 9 5 0 ▁he ▁published ▁C urr icul um ▁Pl anning ▁and , ▁a ▁de cade ▁later , ▁Second ary ▁School ▁C urr icul um . ▁He ▁also ▁wrote ▁Charles ▁W . ▁Eli ot ▁and ▁Popular ▁Education ▁( 1 9 6 1 ) ▁and ▁Sal ient ▁D ates ▁in ▁American ▁Education ▁( 1 9 6 6 ). ▁He ▁collabor ated ▁on ▁School s ▁and ▁Our ▁Democratic ▁Society ▁( 1 9 5 2 ), ▁Mult z ple - Period ▁Organ ization ▁in ▁Wisconsin ▁Second ary ▁School s ▁( 1 9 5 2 ), ▁Admin ister ing ▁C urr icul um ▁Pl anning ▁( 1 9 5 7 ) ▁and ▁The ▁College - Pre par atory ▁Function ▁in ▁Wisconsin ▁High ▁School s ▁( 1 9 5 9 ). ▁ ▁His ▁legacy , ▁though , ▁was ▁established ▁by ▁a ▁two - volume ▁study ▁of ▁the ▁American ▁high ▁school , ▁The ▁Sh