▁number ▁and ▁arithmetic , ▁geometry , ▁data , ▁measurement ▁and ▁early ▁algebra . ▁Un like ▁traditional ▁methods , ▁the ▁original ▁edition ▁did ▁not ▁provide ▁student ▁text books ▁to ▁describe ▁standard ▁methods ▁or ▁provide ▁solved ▁examples . ▁Instead , ▁students ▁were ▁gu ided ▁to ▁develop ▁their ▁own ▁invent ed ▁algorithms ▁through ▁working ▁with ▁concrete ▁representations ▁of ▁number ▁such ▁as ▁manip ul atives ▁and ▁draw ings ▁as ▁well ▁as ▁more ▁traditional ▁number ▁sentences . ▁Add itional ▁activities ▁include ▁journal ing , ▁cutting ▁and ▁past ing , ▁interview ing ▁( for ▁data ▁collection ) ▁and ▁playing ▁concept ual ▁games . ▁ ▁Investig ations ▁released ▁its ▁second ▁edition ▁for ▁ 2 0 0 6 ▁that ▁continues ▁its ▁focus ▁on ▁the ▁core ▁value ▁of ▁teaching ▁for ▁understanding . ▁The ▁re vised ▁version ▁has ▁further ▁emphas is ▁on ▁basic ▁skills ▁and ▁computation ▁to ▁complement ▁the ▁development ▁of ▁place ▁value ▁concepts ▁and ▁number ▁sense . ▁ ▁It ▁is ▁also ▁easier ▁for ▁teachers ▁to ▁use ▁since ▁the ▁format ▁is ▁more ▁user ▁friendly , ▁though ▁some ▁districts ▁have ▁failed ▁to ▁carefully ▁implement ▁the ▁second ▁edition ▁as ▁well , ▁and ▁moved ▁back ▁to ▁text books ▁that ▁teach ▁traditional ▁arithmetic ▁methods . ▁ ▁Research ▁ ▁A ▁system atic ▁review ▁of ▁research ▁into ▁Investig ations ▁was ▁conducted ▁by ▁the ▁U . S . ▁Department ▁of ▁Education , ▁Institute ▁of ▁Education ▁Sciences ▁and ▁published ▁as ▁part ▁of ▁the ▁What ▁Works ▁Clear ing house ▁in ▁February ▁ 2 0 1 3 . ▁This ▁found ▁" pot entially ▁positive ▁effects " ▁on ▁mathematics ▁achiev ement , ▁supported ▁by